RILSAN® Polyamide 11 in Oil & Gas Off - HCL Fasteners Ltd

RILSAN ® Polyamide 11
in Oil & Gas
Off-shore Fluids
Compatibility Guide

After 14 years of research in a program
launched in 1958 by the French Institut de
Petrole, polyamide 11 was chosen as the
best material out of several hundred
tested. Today RILSAN ® polyamide 11, the
unique polyamide from ATOFINA, looks
back at a service history of over 30 years
in the petroleum industry. The combined
qualities of flexibility, excellent impact
resistance even at low temperatures, high
resistance to aging and good compatibility
with products common to the petroleum
industry environment have made RILSAN
polyamide 11 an unequaled standard.
For even higher demands, especially at
higher temperatures or when the
combined high temperature and high
water content requirements are too
severe, ATOFINA proposes its unique
KYNAR ® off-shore grade. KYNAR is a
thermoplastic fluoropolymer resin
developed by ATOFINA. Outstanding
thermomechanical properties combined
with exceptional chemical and aging
resistance enable KYNAR to meet the
most stringent demands.
The data given in this brochure describe the material performance of RILSAN ® polyamide 11 in applications such as
pneumatic or hydraulic tubes. For large diameter pipes or sheaths such as in flexible pipe the data give indications
of lifetime limits, but further considerations might have to be taken into account. Hence this data may be inapplicable
where lifetime and design specifications established by flexible pipe manufacturers or joint industry efforts have
resulted in new recommended practices or industry specifications.

1
2
3
PA11
CONTENTS
1 General introduction and material overview Page 2
1.1 Introduction to thermoplastic polymers 3
1.2 General guide for the use of polyamide 11 3
2 Technical data: RILSAN ® BESNO P40 TLO resin 5
2.1 Mechanical properties and design parameters 5
2.2 Thermal properties 5
3 Overview of aging properties and chemical compatibility 7
3.1 Heat aging 7
3.2 UV aging 8
3.3 Chemical aging 9
3.4 Chemical resistance tables – RILSAN ® BESNO P40 resin grades 10
3.5 Aging in water and acidic solutions – hydrolysis 15
3.6 Influence of methanol on aging and mechanical
properties, permeability data 17
3.7 Influence of monoethyleneglycol and ethyleneglycol
based hydraulic liquids on mechanical properties 19
3.8 Compatibility of RILSAN ® BESNO P40 TLX and BESNO P40 TLO
resins with various offshore fluids and chemicals 21
3.8.1 Demulsifiers 22
3.8.2 Corrosion inhibitors– oil soluble 22
3.8.3 Corrosion inhibitors – water soluble 23
3.8.4 Corrosion inhibitors – oil soluble and water dispersible 24
3.8.5 Oxygen scavengers 24
3.8.6 Biocides 25
3.8.7 Paraffin inhibitors 26
3.8.8 Scale inhibitors 27
3.8.9 Overview of chemical compatibility of RILSAN ® BESNO P40 TLX
and BESNO P40 TLO resins with common offshore chemicals 27
3.9 Compatibility with crude oil, natural gas,
carbon dioxide (CO2) and hydrogen sulfide (H2S) 29
3.9.1 Compatibility with crude oil 29
3.9.2 Compatibility with natural gas 29
3.9.3 Compatibility with carbon dioxide (CO2) 30
3.9.4 Compatibility with hydrogen sulfide (H2S) 30
3.10 Data on permeability of polyamide 11 30
3.11 Blistering resistance 31

2
1
General introduction and
material overview
The term umbilical is applied to
connective systems between underwater
equipment such as wellheads, subsea
manifolds or remote operated vehicles
(ROVs).
An umbilical generally consists of a group
of hydraulic lines, injection lines and/or
electrical cables bundled together in a
flexible arrangement, sheathed and
sometimes armored for mechanical
strength and/or a specific buoyancy.
Related information describing
recommended practice can be found in
the API documents 17R, but also in
API 17B and API 17J on flexible pipes.
Specific examples of structures are given
below.
Fig.1 Umbilical cross sections
PA11 hydraulic
hose 1/2”
1
PA11 hydraulic
hose 1”
PP fillers
A range of materials comes into play to
make up the entire structure:
• carbon steel for the armor
• metals for electrical wire
• cable sheathing
• different thermoplastics for the
injection and hydraulic lines
• fiber reinforcement, often aramid
fibers are used
• outer sheathing of umbilical, often
polyethylene or polyurethane
• duplex steel for hydraulic lines
Extruded pipe made from polyamide 11,
in combination with an aramid braiding
and subsequently sheathed with another
layer of polyamide, provides a very
reliable hose possessing high flexibility,
very high pressure performance, unlimited
seamless tube length and long life in
harsh offshore environments.
Power cables
Tape binder
PE sheath
PP separator
Steel armor wires and outer sheath Steel armor wires
Outer sheath
PP fillers
PA11 hydraulic
hose 1/2”

Fig. 2 Morphology of a semicrystalline polymer
a. b.
●
●
● ●
●
●
●
●
●
●
● ● ●
●
●
● ● ●
●
●
d.
a. repeat unit cell b. crystalline (lc) and amorphous
(la) domains within the long period Lp (lamellar
structure) c. a stack of lamelle d. the spherolite.
1.1 Introduction to thermoplastic
polymers
Thermoplastic polymers are a class of
materials with a wide range of flexibility,
a medium range of elasticity and a wide
range of upper temperature limits. For
semicrystalline materials, their maximum
use temperatures are limited by the
melting point of the crystalline phase.
An image of the general structure of a
semicrystalline thermoplastic material is
given above. The properties of such a
material are governed by the interplay of
the crystalline phase giving strength and
temperature resistance and the amorphous
phase rendering the material
tough and flexible. Typical examples of
semicrystalline polymers are high density
polyethylene (HDPE), polyamide 11 or
nylon 11 (PA11) and polyvinylidene
fluoride (PVDF).
c.
lc
la
L p
The following table gives an outline of the scope of properties of thermoplastic
polymers which can be found in offshore applications today.
COMPARISON OF DIFFERENT THERMOPLASTIC POLYMERS USED IN OFFSHORE SERVICE
PVC HDPE PA11 PVDF
Density (g cm-3) 1.38 – 1.40 0.95 – 0.98 1.03 1.78
Melting Point (°C) 80 130 – 135 188 160 – 170
Flexural modulus (MPa) 1100 – 2700 700 – 1000 300 – 1300 800 – 2000
Tensile strength (MPa) 50 – 75 20 – 30 25 – 30 37 – 48
Shore D hardness 55 – 70 32 – 61 75 – 77
LOI (%) 42 5.7 26 44
1.2 General guide for the use of polyamide 11
Polyamide 11 is a specialty nylon. It combines high ductility, excellent aging resistance
and high barrier properties with mechanical strength and resistance to creep and fatigue.
It thus compares advantageously to standard nylons such as 6 and 66. Notably its significantly
lower water absorption results in better aging resistance, higher chemical resistance
and less property fluctuation due to plasticization by water.
COMPARISON OF DIFFERENT POLYAMIDES
PA 66 PA 6 PA 11 PA 11
plasticized
Melting point (°C) 255 215 188 184
Density 1.14 1.13 1.03 1.05
Flexural modulus (MPa)
50% RH (23°C) 2800 (1200) 2200 1300 300
Water absorption
50% RH (23°C) 2.5 2.7 1.1 1.2
in water immersion 8.5 9.5 1.9 1.9
Charpy notched impact
ISO 180/1A (kJ/m 2 )
23°C 5.3 (24) 8 (30) 23 N.B.
- 40°C X X 13 7
ISO 527
Tensile stress (MPa) 87 (77) 85 (70) 36 21
Tensile elongation (%) 5 (25) 22 –
Elongation at rupture (%) 60 (300) 15 – 200 360 380
N.B. = no break, values in parentheses at elevated humidities, RH = relative humidity
3

4
The excellent properties of polyamides
and in particular polyamide 11 are a result
of the amide linkages in the chain which
allow a strong interaction between the
chains by hydrogen bonds. Low creep,
high abrasion resistance, good resistance
to fatigue and high barrier properties are
a direct result of these strong inter-chain
links.
Molecules which can create hydrogen
bonds such as water, methanol, ethanol,
ethylene glycol can penetrate polyamide
11 and lead to plasticization. They can
interfere in inter-chain hydrogen bonds
thus weakening the hydrogen bond network.
Especially methanol has a significant
absorption rate and must be considered
in certain applications. Please refer
to section 3.6.
H–N
O=C
H–N
O=C
PA CHAINS WITH H-BONDING
C=O
N–H
N–H
IIIIIII
IIIIIII
H–N
O=C
C=O IIIIIII H-N
IIIIIII O=C
C=O IIIIIII H–N
N–H IIIIIII O=C
C=O IIIIIII H–N
N–H IIIIIII O=C
C=O
H–N
C=O
Although polyamide 11 is highly resistant
to aging and chain breakdown, the reaction
of water with amide bonds creates a
limit to the use of polyamide at higher
temperatures and in the presence of
water. The specific reaction induced by
water, called hydrolysis, can be accelerated
in the presence of acids. At continuous
service temperatures of 65°C and below,
the impact of hydrolysis on polyamide 11
in a neutral medium such as water can be
neglected. Under these conditions, the
material can have a service life of 20 years
or more. The use at higher continuous
service temperatures depends on the performance
requirements and more precise
conditions. The reader should refer to
data on temperature – lifetime correlations
in section 3.5.
O
=
REACTION: HYDROLYSIS
vvvvv C–Nvvvvv +H2O →
← vvvvv CO2H + vvvvv NH2
–
H
A special molecule, butyl-benzene-sulfonamide
or BBSA, has been chosen as a
plasticizer. It has very low volatility and
leads to an efficient plastification of the
resin. Questions related to its extraction
or its influence on material properties are
discussed in section 3.7.
BUTYL-BENZENE-SULFONAMIDE OR BBSA
O II
SII
O
N
H
A range of RILSAN ® polyamide 11 grades
has been developed to correspond to the
specific needs of the oil and gas industry.
BESNO P40 TL
A high viscosity and plasticized grade
developed for pipe extrusion.
BESNO P40 TLX
A high viscosity and plasticized grade
developed for pipe extrusion especially
for the inner pressure layer of flexible
pipe.
BESNO P40 TLO
A high viscosity and plasticized grade
developed for pipe extrusion with a low
extractable content especially adapted for
hydraulic hoses in umbilicals.
The blooming of oligomers has clogged
valves or filters in subsea installations.
Oligomeric molecules present in the
polymerized PA11 resin are extracted and
the material is compounded with a
plasticizer and heat additives.
BESNO P20 TL
A medium plasticized, high viscosity extrusion
grade for pipe and sheath extrusion.
BESNO TL
A high viscosity unplasticized grade
adapted for pipe extrusion.
BMNO TLD
An injection molding grade.
These grades are all of natural color.
Certain colored grades or color master
batches are also available.

2
Technical data: BESNO P40 TLO
BESNO P40 TLO is a plasticized and
washed polyamide 11 grade. The
methanol washing process eliminates
low molecular weight extractables
(chemical name: oligomers) which can
lead to fouling or clogging of the filters
or needle valves.
2.1 Mechanical properties and
design parameters
DENSITY
ASTM D792 1.05 g/cm 3
HARDNESS
ISO 2039/2 (R SCALE) 75
ISO 868 (D SCALE) 61
COMPRESSION STRENGTH
ASTM D695 (23°C) 50 MPa
ABRASION RESISTANCE
ISO 9352 : 1995(F)
(loss in weight after 1000 rev under
500g H18 wheel) 22 mg
FLEXURAL TESTS ACCORDING TO ISO 178 : 93
Temperature °C -40 -20 23 80
Flexural modulus MPa 1950 1350 320 165
(dry material)
Flexural modulus MPa 2050 1150 280 160
(after conditioning 15
daysat23°C, 50% R.H.)
FLEXURAL TESTS ACCORDING TO ASTM D790
Temperature °C 23 80
Flexural modulus MPa 330 170
(dry material)
IMPACT TESTS ACCORDING TO ISO 179 (type 1)
Temperature °C -40 23
Unnotched KJ.m -2 N.B. N.B.
Notched KJ.m -2 8 N.B.
N.B. = no break
IMPACT TESTS ACCORDING TO ISO 179 :93 CA
Temperature °C -40 -20 0 23
Notched KJ.m -2 6.8 9.9 52.9 N.B.
2.2 Thermal properties
THERMAL CONDUCTIVITY
Temperature (°C) 39 61 82 102 122 142 163 182 202 223
K(W/m°K) 0.21 0.24 0.24 0.24 0.24 0.24 0.25 0.25 0.25 0.25
THERMAL EXPANSION HEAT DISTORTION TEMPERATURE SOFTENING POINT
ASTM E 821 ASTM D648 ASTM D1525
from -30°C to +50°C 11x10 -5 °K -1 ISO 75 (0.46 Mpa) 130 °C under 1 daN 170 °C
from +50°C to +120°C 23x10 -5 °K -1 ISO 75 (1.85 Mpa) 45 °C under 5 daN 140 °C
5

6
Measured by D.S.C.
HEAT CAPACITY
Temperature (°C) 20 50 80 120 160 200 230 260
cal/g.°C 0.40 0.50 0.6 0.6 0.65 0.65 0.65 0.65
D.M.A. 0-10 °C
DYNAMIC MECHANICAL ANALYSIS
(full curve)
The DMA curve obtained is characteristic
for semicrystalline polymers. Essentially
four different temperature zones can be
described which are related to characteristic
relaxational transitions.
The first zone is a low temperature high
modulus zone which starts to soften
around –20°C. Due to efficient low temperature
relaxations (centered around
–80°C) PA11 is tough even at these very
low temperatures.
Between –20 and 40°C the material softens
gradually to attain its characteristic
STORAGE MODULUS E' (Pa) LOSS MODULUS E" (Pa)
1.00E+10
1.00E+09
1.00E+08
GLASS TRANSITION TEMPERATURE
flexibility. This softening is due to the
onset of motion, the glass transition, in
the amorphous regions. From 40 to 160°C,
the PA11 modulus remains very stable
due to the crystalline phase with its
onset of melting starting only around
160°C. The fine distribution of the crystalline
phase and its constant modulus,
largely independent of temperature,
guarantee very stable mechanical
properties over a very wide temperature
range and a high resistance to creep.
For a textbook on the comprehensive
analysis of DMA data refer to Anelastic
and Dielectric Effects in Polymer Solids by
N.G. McCrum, B.E. Read, G. Williams;
Dover Publication, New York, 1991.
1.00E+07
-140 -120 -100 - 80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180
TEMPERATURE ( °C)
Fig. 3 BESNO P40 TL – plasticized PA11 Measurement in a 3-point bending flexural mode at 10 rad/s
E'
E"

3
Overview of aging properties of
polyamide 11
Polyamide 11 is subject to aging phenomena.
These phenomena are rather
varied and depend on the specific environment.
The most important factors
inducing aging and subsequent loss of
properties for polyamides are:
• Heat
• UV light
• Chemicals
Alldata given in the following chapters
refer to BESNO grades. The suffix “P40”
signifies a plasticized grade.
“TL” and “TLX” signify various heat and
light stabilizer packages.
The suffix “TLO” signifies an oligomer
extracted grade which is heat and light
stabilized.
3.1 Heat aging
Heat in the presence of oxygen causes oxidative degradation. For the reaction of
oxygen with an organic polymer to take place, oxygen molecules must diffuse into the
bulk polymer from the outside. Reactions occur first on the surface, leading to surface
embrittlement.
Oxidative degradation can be efficiently suppressed by anti-oxidants. All RILSAN ® PA11
grades used in offshore applications have specially suited anti-oxidant packages. In
the grade nomenclature, this is notified by a suffix “TL.”
Heat aging performance has been established based on accelerated tests in a ventilated
oven. In most cases the performance is monitored by tensile experiments. An
example of a typical test series isgiven in the figure below.
ELONGATION AT BREAK (%)
500
450
400
350
300
250
200
150
100
50
•
0
•
50
•
•
•
100 150 200 250 300 350
TIME (HOURS)
Fig. 4 Reduction of elongation at break: BESNO P40 TLX aged at 155°C
•
• mean values
•
7

8
LOG TIME (DAYS)
ELONGATION AT BREAK (%)
4
3.5
3
2.5
2
1.5
1
.5
0
■■■ 20 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 10 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 5 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 1 YEAR ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
+ + + + + + + +
150 140 130 120 110 100 90 80
TEMPERATURE ( °C)
Fig. 6 Laboratory aging of BESNO P40 TLX: Xenotest 1200
400
350
300
250
200
150
100
50
Fig. 5 Laboratory aging as a function of temperature – half times from elongation at break
are taken from injection-molded and machined samples – material is BESNO P40 TLX. The
influence of poorer surface quality on aging performance is demonstrated.
•
0
•
•
+
Machined
Injected
Linear (machined)
Linear (injected)
500 1000 1500 2000 2500
TIME (HOURS)
TIME (h) 0 500 1000 1400 2000
EB (%) 380 330 275 85 33
EB/EB 0 1 0.87 0.72 0.22 0.09
MB (MPa) 72 61 47 34 25
YI 6 14 16 13 13
EB = elongation at break, MB = modulus at break, YI = yellowness index
•
•
3.2. UV aging
UV light in conjunction with oxygen leads
to similar surface degradation effects as
heat degradation. Effective anti-UV light
stabilizing packages are routinely
employed to protect the resin (marked by
suffix “TL”). Different tests have been
developed to simulate the impact of UVlight
combined with natural weathering.
These tests include cycles where the samples
are alternatively subject to moist heat
and UV light.
The UV resistance is measured under
accelerated conditions on a standardized
machine, XENOTEST 1200, according to
the RENAULT standard no. 1380. Results
are shown in Figure 6.
Conditions:
Xenon lamps with filters eliminating radiation
with wave lengths less than to 300 nm.
Intermittent exposure – equal periods of
light and darkness.
During a 20 minute cycle, the specimens
are exposed to 3 minutes of distilled
water spray and 17 minutes of exposure
without spraying. The relative humidity of
the cabinet during period without spray is
approximately 65%.
Black panel temperature in the measurement
cabinet:
65°C ± 2°C before spraying
45°C ± 2°C after spraying
The specimens are dumbells according to
ISO/NFT 51034 cut from a film of 1 mm
thickness. Tensile tests are carried out at
50 mm/minute.

3.3 Chemical aging
In offshore applications, certain offshore
fluids and chemicals can have a detrimental
effect on polyamide 11 performance. For
each application, the specific chemicals
should be reviewed in order to estimate
service life.
Polyamides, and in particular polyamide
11, are very resistant to many types of
chemicals. Polyamide 11 is very resistant
to oils and hydrocarbons as well as to a
large variety of solvents. In contrast to
standard polyamides 6 and 66; polyamide
11 shows only little absorption of water
and is also resistant to diluted acids and
bases. Due to its increased flexibility and
molecular structure, it is also highly resistant
to stress cracking, unlike most other thermoplastics.
Polyamide 11 can be used in conjunction
with a great variety of standard offshore
chemicals. A detailed description of compatibilities
is given in sections 3.8 and 3.9.
Because chemical species attack thermoplastic
resins when they are absorbed,
diffusion and solubility play important roles
in the assessment of chemical compatibility.
There are two effects induced by absorbed
species – an influence on the mechanical
properties due to plasticization, and a
chemical effect leading to loss of material
performance.
Specific examples of absorption and
plasticizer extraction are given in sections
3.6 and 3.7 on methanol-and glycol-based
hydraulic liquids.
The main chemical effect is reduction in
polymer molecular weight due to hydrolysis.
Hydrolysis is the reverse reaction of the
chain-forming polycondensation reaction.
It can be induced by water at elevated
temperatures and is accelerated by acids
and, to some extent, also by bases. Due to
the importance of hydrolysis in aging related
to offshore applications, section 3.5
describes the phenomenon in detail.
ELONGATION AT BREAK (%)
Fig. 6A Evolution of Yellowness Index (YI) in Xenotest aging
40
35
30
25
YI 20
15
10
5
•
0
•
•
500 1000 1500 2000 2500
TIME (HOURS)
EQUILIBRIUM SWELLING AND CHEMICAL COMPATIBILITY
OF COMMON SOLVENTS AND OFF SHORE FLUIDS
Solvent Swelling at 20°C in % weight Compatibility
Benzene 7.5 good up to 70°C / swelling
Toluene 7 good up to 90°C / swelling
Cyclohexane 1 good
Petrol ether 1.5 good
Decaline < 1 good
Gasoline depends on type, mostly < 2% good
Kerosene depends on type, mostly < 2% good
Ethylene glycol 2.5 good up to 60°C / swelling
Glycerol 1 good up to 60°C
•
•
9

10
3.4. Chemical resistance table – BESNO P40 grades
The following tables give a first impression of chemical
resistance of PA11 extrusion resins.
G: good
L: limited (important swelling or dissolution)
P: poor
Index * denotes swelling, indexb denotes discoloration
(brownish or yellowish)
Inorganic Salts
Concentration 20°C 40°C 60°C 90°C
calcium arsenate Concentrated or paste G G G
sodium carbonate Concentrated or paste G G L P
barium chloride Concentrated or paste G G G G
potassium nitrate Concentrated or paste G b L b P P
diammonium phosphate Concentrated or paste G G L
trisodium phosphate Concentrated or paste G G G G
aluminium sulphate Concentrated or paste G G G G
ammonium sulphate Concentrated or paste G G L
copper sulphate Concentrated or paste G G G G
potassium sulphate Concentrated or paste G G G G
sodium sulphide Concentrated or paste G G L
calcium chloride Concentrated or paste G G G G
magnesium chloride 50% G G G G
sodium chloride saturated G G G G
zinc chloride saturated G G L P
iron trichloride saturated G G G
barium formate saturated G L P
sodium acetate saturated G L P

Other Inorganic Materials
Concentration 20°C 40°C 60°C 90°C
water See section 3.5 G G G G
sea water G G G G
carbonated water G G G G
bleach L P P P
hydrogen peroxide 20% G L
oxygen G G L P
hydrogen G G G G
ozone L P P P
sulphur G G
mercury G G G G
fluorine P P P P
chlorine P P P P
bromine P P
potassium permanganate 5% P P
agricultural sprays G G
Organic Bases
aniline Pure L P P P
pyridine Pure L P P P
urea G G L L
diethanolamine 20% G G* G* L
Inorganic Bases
sodium hydroxide 50% G L P P
potassium hydroxide 50% G L P P
ammonium hydroxide concentrated G G G G
ammonia liquid or gas G G
11

12
Inorganic Acids
Concentration 20°C 40°C 60°C 90°C
hydrochloric acid 1% G L P P
10% G L P P
sulphuric acid 1% G L L P
10% G L P P
phosphoric acid 50% G L P P
nitric acid P P P P
chromicacid 10% P P P P
sulphur dioxide L P P P
Halogenated solvents
methyl bromide G P
methyl chloride G P
trichloroethylene L P
perchloroethylene L P
carbon tetrachloride P
trichloroethane L P
Freon G
Phenols P P P P
Esters and Ethers
methyl acetate G G G
ethyl acetate G G G
butyl acetate G G G L
amyl acetate G G G L
tributylphosphate G G G L
dioctylphosphate G G G L
dioctylphthalate G G G L
diethyl ether G
fatty acid esters G G G G
methyl sulphate G L

Various Organic Compounds
Concentration 20°C 40°C 60°C 90°C
anethole G
ethylene chlorohydrin P P L
ethylene oxide G G P P
carbon disulphide G L L
furfuryl alcohol G G
tetraethyl lead G
diacetone alcohol G G L P
glucose G G G G
Organic Acids and Anhydrides
acetic acid refer to section 3.5 – role of acidity in hydrolysis
L P P P
acetic anhydride L P P P
citric acid G G L P
formic acid P P P P
lactic acid G G G L
oleic acid G G G L
oxalic acid G G L P
picric acid L P P P
stearic acid G G G L
tartaric acid G G G L
uric acid G G G L
13

14
Hydrocarbons
Concentration 20°C 40°C 60°C 90°C
methane G G G G
propane G G G G
butane G G G G
acetylene G G G G
benzene G G L P
toluene G G L L
xylene G G L L
styrene G G
cyclohexane G G G L
naphthalene G G G L
decalin G G G L
crude oil G G G L
Alcohols
methanol Pure G L P
ethanol Pure G L P
butanol G L P
glycerine pure G G L P
glycol G G L P
benzyl alcohol L P P P
Aldehydes and Ketones
acetone Pure G G L P
acetaldehyde G L P
formaldehyde G L P
cyclohexanone G L P
methylethylketone G G L P
methylisobutylketone G G L P
benzaldehyde G L P

AGING TEMPERATURE (°C)
150
140
130
120
110
100
90
80
70
60
3.5 Aging in water and acid solutions – hydrolysis
In many offshore conditions, the performance loss for polyamide 11 has been linked to
a chain scission mechanism due to a reaction with water. Polyesters, polyamides and
polyurethanes are created by polycondensation. The polycondensation reaction creating
the long chains is reversible and the opposite reaction is called hydrolysis. Among the
cited polymers, polyamide 11 is particularly resistant to hydrolysis due to its low
moisture absorption (~2% water at saturation).
vvvvv CO2H + vvvvv NH2 →
← vvvvv C–Nvvvvv +H2O
polycondensation =>

16
An aggravating factor for the hydrolysis
process is the presence of acids – either
carbonic acid produced under CO2 pressure
or naphthenic acids possibly present
in crude oil.
Carbonic acid formed by the dissolution
of carbon dioxide in water under pressure
causes a more severe polymer performance
loss than gaseous carbon dioxide.
In the case of naphthenic acids, the larger
molecule size slows its diffusion into the
polymer. In this case, a distinct surface
attack or a gradient over the sample thickness
can be observed.
LIFETIME (DAYS)
LIFETIME (DAYS)
100000
10000
1000
100
10
1
100000
10000
1000
100
10
1
Fig. 8 Hydrolysis resistance as a function of pH
■■■ 20 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 10 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 5 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 1 YEAR ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■
• ■ ▲
■
▲
■
•
■
▲■
•
140 130 120 110 100 90 80 70
Fig. 9 Aging behavior as a function of pH
■
▲
•
TEMPERATURE ( °C)
TEMPERATURE ( °C)
■
▲
■
•
■
■
pure water pH=7
pH=5 CO2 liquid
pH=4 CO2 gas
pH=4 CO2 liquid
■■■ 20 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 10 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 5 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 1 YEAR ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
• ■
■
•
◆
■
■
•
◆
140 130 120 110 100 90 80 70
■
•
◆
■
■
•
◆
■
pure water pH=7
pH=4 CO2 liquid
Strong organic acid

METHANOL ABSORPTION WT. %
3.6 Influence of methanol on aging and mechanical
properties, permeability data
Methanol is a widely used injection fluid. For example, it is efficient
in dissolving gas hydrates formed during a gas production
pipe shut-down. Methanol, due to its small molecule size and its
high solubility, has a high permeation rate through PA11. It is
also an efficient solvent for plasticizer extraction. In spite of
these unfavorable factors, methanol can be successfully used in
conjunction with PA11 hydraulic tubes.
Methanol affects the material performance of PA11 in
several ways:
• A swelling effect accompanied by plasticization. At temperatures
of 140°C and above, methanol becomes a solvent for PA11.
• Plasticizer extraction.
• A methanolysis reaction which leads to a loss of
polymer molecular weight.
O O
CH3OH + vvvvv N – H2 – C vvvvv →
← vvvvv NH2 + vvvvv C – OCH3
H
50
45
40
35
30
25
20
15
10
5
–
• • •
=
•
0 20 40 60 80 100 120 140 160
TEMPERATURE (°C)
Fig.10 Methanol absorption of BESNO P40 grades
•
•
=
The effect of methanol absorption on mechanical properties is
outlined in the figure below.
STRESS AT RUPTURE (MPa)
60
50
40
30
20
10
•
•• • •
0 5 10 15 20 25 30 35 40 45
TIME (DAYS)
Fig. 11 Methanol aging: Stress at rupture in time at 40°C
A rapid drop in strength as measured by stress at rupture is
observed due to deplasticization. The resin strength then equilibrates
in methanol leading to stable properties.
Extraction of plasticizer and swelling due to methanol change
the modulus, but this is not an aging effect. Once the modulus
after methanol conditioning is attained, it remains stable. The
long-term stability of polyamide 11 in methanol is further
demonstrated in experiments outlined below.
Long term aging data of PA11, BESNO P40 TLO in methanol
Small dogbone samples are immersed at a given temperature in
methanol in an autoclave. After a given time, five samples are
retrieved and tensile tests are performed.
DATA AT 40°C
Time (days) Stress at rupture (MPa) Elongation at rupture (%)
0 53 ± 0.86 438 ± 13
40 42.2 ± 2.63 597 ± 34
100 42.9 ± 0.9 646 ± 22.6
150 42.8 ± 2.71 667 ± 31.7
250 40.6 ± 1.94 591 ± 46
300 39.7 ± 1.4 603 ± 51
360 43.2 ± 1.4 646 ± 28.8
410 37.4 ± 2.2 561 ± 32.5
At 40°C, the plasticizer is extracted after 2 days. The initial
decrease of the stress at rupture is due to a plasticization effect
of absorbed methanol.
17

18
DATA AT 70°C
Time (days) Stress at rupture (MPa) Elongation at rupture (%)
0 53 ± 0.86 438 ± 13
1 31.9 ± 2.58 419 ± 25.1
2 32.8 ± 3.43 419 ± 32.8
8 33.7 ± 2.48 432 ± 19.6
42 34.9 ± 3.02 440 ± 22.7
120 33.8 ± 4.3 460 ± 44
160 33.1 ± 3.8 442 ± 30
2000 (5 1/2 years) 32 ± 5 320 ± 40
The plasticizer is extracted after 2 hours at 70°C. The strong plastification effect of
methanol more than compensates for the plasticizer loss. The material becomes more
flexible. At 70°C, Rilsan ® PA11 is not significantly degraded.
All these factors lead to the following picture for a service life – temperature relationship:
LIFETIME (DAYS)
100000
10000
1000
100
10
1
Fig. 12 Polyamide 11, BESNO P40 grades – lifetime in methanol contact
■■■ 20 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
120 110 100 90 80 70 60 50
TEMPERATURE ( °C)
water, pH=7
methanol

PERMEABILITY (G.MM/M 2.DAY)
1000
100
10
1
METHANOL PERMEATION DATA
Temperature in °C 4 23 40 50
PA11 unplasticized 6 18
PA11 plasticized 13.5 40 115 190
units: g mm/m 2 day atm
The activation energies for the unplasticized and plasticized
grades are respectively:
39.4 kJ mol-1 and 43.1 kJ mol-1. Fig. 13 Methanol permeability
■
■
• BESNO TL
■ BESNO P40TL
50°C 40°C 30°C 20°C 10°C 0°C
1/TEMPERATURE
Pressure effects on permeability have been observed. As a
general rule, a tenfold increase in pressure results in a three-fold
increase in methanol permeation.
Conclusions:
• Methanol has a finite permeation rate through PA11 which has
to be taken into account in design.
•Liquid methanol efficiently extracts the plasticizer from PA11
plasticized grade “P40”. For umbilicals, this extraction has no
consequence on the integrity of the pipe.
• Methanol induces a softening and also polymer breakdown at
higher temperatures. We suggest 70°C as the maximum continuous
use temperature and 90°C for occasional temperature
peaks in the case of hydraulic hoses. For offshore flexible
pipes, the extraction of plasticizer and the modification of the
flexiblity can further reduce the continuous use temperature.
■
•
■
•
3.7 Influence of monoethylene glycol and ethylene
glycol-based hydraulic liquids on mechanical
properties
Monoethylene glycol and other ethylene glycols mixed in
different ratios with water are used as constituents of hydraulic
liquids in offshore applications. These liquids can extract plasticizer
from polyamide resin because the plasticizer has a rather
high solubility in glycol/water mixtures. This effect is shown in
the graph below. The tensile yield shifts to higher
modulus with the departure of the plasticizer.
To some extent glycol/water mixtures act as plasticizer themselves
when absorbed by polyamide 11 resin.
All these phenomena are well known today and experience has
shown that they do not cause any particular problem in the
functioning of the subsea installation under ordinary working
conditions.
In the following, the phenomena are described in detail so that a
thorough understanding of the prevailing material behavior can
be developed.
STRESS AT YIELD (MPa)
40
35
30
25
20
15
10
5
Fig. 14 Evolution of tensile stress of BESNO P40 TL 12mm bore
hoses in water/glycol 60/40
0 200 400 600 800 1000
TIME (DAYS)
40°C
70°C
19

20
The physical picture of the interactions
In a physical description of the ensemble
“umbilical filled with control fluid,” we
have to consider a closed system with
two phases, PA11 and control fluid, and
several components which, in time, can
interdiffuse between the two phases.
These components are the plasticizer
BBSA and constituents of the control
fluid, mainly glycols.
Control Fluid
The effects can be described when the
solubility parameters of the diffusing
species and the diffusion kinetics are
known. The mathematics of diffusion in a
plane sheet are well described (Crank).
We will use some simple forms to illustrate
the effects in a semiquantitative
manner.
For a particular umbilical, the ratio
between the two phases may be different
due to the particular tube dimensions.
The approach is best described in a
worked example.
Standard 1 /2’’ hydraulic tube
ID = 12 mm WS = 1.5 mm
OD = 15 mm L = 100 mm
...................
...................
OD ID
...................
...................
BBSA BBSA
We calculate:
Fluid volume: 11.3 ml
Weight of tube (r = 1.05 mm): 5.4 g
The plasticizer content is on average
12.5% by weight of the resin.
BBSA content in a tube
with L = 100 mm: 675 mg
L
PA11
BBSA SOLUBILITY (G/L)
14
12
10
8
6
4
2
60°C
22°C
0 5 10 15 20 25 30 35 40 45
GLYCOL CONTENT ( %)
Fig. 15 The solubility of BBSA in glycol-based control fluids and its temperature
dependence
The maximum extractable amount of plasticizer adds up to approximately 6% by
weight. For a hydraulic fluid containing 45% glycol, the maximum plasticizer solubility
at ambient temperature is close to 6%. For a hydraulic fluid containing 25% glycol, the
solubility limit is 2.2 – 2.5%. At temperatures over 60°C, the plasticizer will be extracted
as it will become soluble in such a fluid.
22°C 60°C
pure water based, eg., Oceanic* HW 500 0.1 - 1 1.5 – 2.5
approx 25% glycol, eg., Oceanic HW 525 2.2 – 2.5 6.8 – 7.4
approx 40% glycol, eg., Oceanic HW 540 4.0 – 5.0 12.0 – 13.6
*Hydraulic fluid manufactured by MacDermid Canning, PLC

3.8 Compatibility of RILSAN® BESNO P40 TLX and
BESNO P40 TLO resin with various offshore fluids
and chemicals
A variety of offshore fluids have specific functions in the exploration
and production process in offshore installations:
• Demulsifiers to break oil/water emulsions
• Corrosion inhibitors to slow corrosion of steel
• Bactericides to suppress the formation of acid-creating
bacteria
• Paraffin inhibitors which prevent the crystallization of
paraffins leading to a blocking of the pipes
• Scale inhibitors which prevent the formation of salt scales
capable of blocking of the pipes
• Oxygen scavengers which help prevent corrosion
Numerous formulations exist depending on the producer and
specific adaptions. However, the nature of the ingredients
remain essentially the same. Often even the compounds remain
the same and given formulations differ only in the amounts of
the constituents. The aim of this chapter is to analyze the behavior
of PA11 when exposed to the specific chemicals used in offshore
applications. It supplements the information in the more
general chemical resistance table in section 3.4.
For convenience, the results of the testsoftypical offshore fluids
are summarized in a final subsection 3.8.9.
For the screening tests, small dogbone samples were autoclaved
at a given temperature immersed in the chosen offshore fluid.
After a given time, 5 samples were retrieved on which tensile
testswere performed, weight changes monitored, and the
molecular weight changes analyzed.
Allcompatibility tests were performed at 60°C. Testing periods
were generally 2 years.
Given the typical activation energy for the chemical degradation
processes, a good behavior after 2 years at 60°C should give a
service life over 20 years at temperatures around 20°C.
21

22
3.8.1 Demulsifiers
Chemicals
• oxypropylated and/or oxyethylated alkylphenol
• ethylene oxide/propylene oxide copolymers
• glycol esters
• condensates of modified propylene oxide/ethylene oxide
• aromatic solvents, C7 to C10
(benzene, toluene, xylene, ethylbenzene)
TEST: PROCHINOR 2948 (AROMATIC SOLVENTS, NON-IONIC SURFACTANT)
Immersion time at 60°C Ultimate tensile Elongation at break Weight Inherent viscosity
strength % change % change % change % change
1 week - 2.7 - 0 + 1.26
1 month + 5.3 0 - 0.43
3 months + 85 + 2.7 - 2.37
6 months + 0.4 - 4.5 – 2.9
12 months + 10.5 + 0
18 months - 4 - 7.2 - 3.16
24 months + 1.4 - 1.2 - 3.26 no change
3.8.2 Corrosion inhibitors – oil soluble
Chemicals
• fatty amines
• imidazoline derivatives
• aromatic solvents
TEST: NORUST ® PA23 (FATTY AMINES, IMIDAZOLINE DERIVATIVES, AROMATIC SOLVENT)
Immersion time at 60°C Ultimate tensile stress Elongation at break Weight Inherent viscosity
(% change) (% change) (% change) (% change)
1 week + 3.6 - 3.6 - 1.13
1 month + 3.4 - 6.3 - 2.0
3 months + 8.7 - 3.3 - 3.17
6 months + 1.8 - 9.0 - 4.07
12 months + 9.7 - 7.5
18 months + 1.0 - 6.0 - 5.37
Comments
None of these chemicals have adverse effect on PA11.
Aromatic solvents exert slight swelling at temperatures above 40°C.
24 months + 5.15 - 10.2 - 5.85 + 1.6

3.8.3 Corrosion inhibitors – water soluble
Chemicals
• fatty amines
• imidazoline derivatives
• sulphite derivatives
• water/glycol mixtures
TEST: NORUST ® 743D (FATTY AMINES, IMIDAZOLINE DERIVATIVES, WATER/GLYCOL MIXTURES)
Immersion time at 60°C Ultimate tensile stress Elongation at Weight Inherent viscosity
(% change) break (% change) (% change) (% change)
1 week - 6.7 - 4.2 - 1.04
1 month + 0.2 - 2.4 - 3.06
3 months + 4.5 - 0.6 - 5.02
6 months + 2.0 - 3.3 - 5.82
12 months + 4.2 - 2.1
18 months + 5.0 + 2.4
24 months + 3.0 - 3.3 - 6.79 0
TEST: NORUST 720 (FATTY AMINES, IMIDAZOLINE DERIVATIVES, WATER)
1 week - 1.4 + 2.7 - 1.03
1 month + 2.2 + 0.9 - 3.22
3 months + 5.9 + 4.8 - 5.7
6 months - 5.7 - 3.0 - 6.63
12 months - 4.7 - 7.8 - 7.54
18 months - 3.0 - 3.6
24 months + 2.6 - 0.6 - 7.55 + 0.8
TEST: NORUST CR486 (FATTY AMINES, SULPHITE DERIVATIVES, WATER/GLYCOL MIXTURE)
1 week - 8.9 - 6.0 - 1.0
1 month - 5.7 - 10.0 - 2.86
3 months + 2.6 - 0.9 - 5.1
6 months - 4.5 - 3.3 - 5.89
12 months - 15 - 12.7
18 months - 36.6 - 38.4 - 6.33
24 months - 42.7 - 50.1 - 5.98 - 38
23

24
3.8.4 Corrosion inhibitors (oil soluble and water dispersible)
TEST: NORUST ® PA23D (FATTY AMINES, IMIDAZOLINE DERIVATIVES, AROMATIC SOLVENT, ALCOHOL)
Immersion time at 60°C Ultimate tensile stress Elongation at break Weight Inherent viscosity
(% change) (% change) (% change) (% change)
1 week + 5.1 - 1.8 - 0.74
1 month + 5.1 - 5.1 - 1.31
3 months + 9.1 + 0.3 - 2.37
6 months + 0.4 - 8.4 - 4.4
12 months + 6.5 - 5.1
18 months + 3.0 - 1.5 – 4.67
24 months + 8.3 - 2.7 - 6.02 + 4.0
3.8.5 Oxygen scavengers
Chemicals
• sodium bisulphite
NORUST SC45
Immersion time at 60°C Ultimate tensile stress Elongation at break Weight Inherent viscosity
(% change) (% change) (% change) (% change)
1 week - 13.6 - 5.4 + 4.23
1 month - 10.3 - 1.5 + 5.78
3 months - 10.5 + 2.1 + 3.94
6 months - 13.9 + 3.6 + 4.67
12 months - 23.2 + 0.9
18 months - 80.2 - 97 + 5.22 - 65
24 months

3.8.6 Biocides
Chemicals
• ammonium quarternary salts
• ammonium salts
• aldehydes
• water/glycol mixtures
TEST: BACTIRAM ® C85 (AMMONIUM QUARTERNARY SALTS, WATER)
Immersion time at 60°C Ultimate tensile stress Elongation at break Weight Inherent viscosity
(% change) (% change) (% change) (% change)
1 week + 0.6 + 1.5 - 0.73
1 month + 8.7 + 5.1 - 2.79
3 months + 7.5 + 0.9 - 4.86
6 months + 7.3 - 0.6 - 5.32
12 months + 3.1 - 3.3
18 months - 6.8
24 months - 3.0 - 7.5 - 8.07 + 5.6
TEST: BACTIRAM CD30 (AMMONIUM SALTS, WATER/GLYCOL MIXTURE)
1 week - 15.8 - 0.6 - 0.09
1 month - 15.4 - 1.8 - 1.87
3 months - 9.3 + 5.7 - 2.44
6 months - 7.9 + 3.6 + 0.48
12 months -12.3 0.0
18 months - 18.8 - 8.8 - 1.59
24 months - 21.8 - 1.5 - 3.19 - 4
TEST: BACTIRAM 3084 (ALDEHYDES, WATER)
1 week - 3.2 - 1.8 + 0.77
1 month + 2.2 + 0.3 - 2.23
3 months + 0.2 - 5.4 - 3.53
6 months 0.0 - 5.4 - 4.1
12 months + 2.4 + 3.6
18 months - 8.9 - 9.4 + 0.65
24 months - 9.1 - 3.9 - 2.02 - 22.6
25

26
3.8.7 Paraffin inhibitors
Chemicals
• non-ionic surfactants
• polyacrylate
• aromatic solvents
TEST: PROCHINOR ® AP 104 (NON-IONIC SURFACTANT, AROMATIC SOLVENTS)
Immersion time at 60°C Ultimate tensile Elongation at break Weight Inherent viscosity
stress (% change) (% change) (% change) (% change)
1 week + 1.4 - 1.5 + 0.8
1 month + 3.2 - 1.2 - 0.43
3 months + 7.5 + 1.2 - 2.44
6 months - 5.9 - 9.4 - 2.9
12 months + 3.0 - 4.8
18 months + 3.0 - 0.6 - 3.38
24 months + 4.9 - 0.1 - 4.35 + 8
TEST: PROCHINOR AP 270 (POLYACRYLATE. AROMATIC SOLVENTS)
1 week - 3.7 + 0.6 + 3.07
1 month + 0.6 - 1.5 - 0.04
3 months + 6.3 + 4.2 - 0.28
6 months + 2.0 + 1.5 + 1.37
12 months + 4.0 + 4.2
18 months - 1.0 + 6.0 - 1.84
24 months - 3.2 - 2.7 + 0.2 - 13.7

3.8.8 Scale inhibitors
Chemicals
• phosphonate
• polyacrylate
TEST: INIPOL ® AD100 (POLYACRYLATE, WATER)
Immersion time at 60°C Ultimate tensile stress Elongation at break Weight Inherent viscosity
(% change) (% change) (% change) (% change)
1 week - 0.6 + 2.7 - 0.58
1 month + 2.6 + 1.8
3 months + 11.5 + 9.4 - 3.83
6 months + 0.8 - 0.3 - 5.64
12 months - 4.9 - 0.9
18 months - 6.9 - 4.5 - 5.48
24 months - 9.7 - 3.6 - 5.5 - 16
TEST: INIPOL AD20 (PHOSPHONATE, WATER)
1 week - 3.4 + 4.5 + 1.88
1 month - 3.6 + 6.0 + 1.98
3 months - 82.2 - 97.8 + 2.5 - 48
6 months
12 months
18 months
24 months
3.8.9 Overview of chemical compatibility of RILSAN ®
BESNO P40 TLX and BESNO P40 TLO with
common offshore chemicals
Offshore fluids are complex mixtures of several functional
chemicals which are either
• water based
• glycol/water mixture based
• hydrocarbon based
To quickly assess the compatibility of a given offshore fluid, it is
useful to examine the active constituents which are most often
given in the safety data sheet. Concentrations of the active
chemical species in the concentrated offshore fluid range
between 3 and 30%. In order to estimate the chemical compatibility,
the most aggressive species must be identified. Its given
temperature limit can be taken as the limit for the given offshore
fluid. In the given list, no two chemicals have a synergistic
degradative effect, but some have antagonistic effects.
Furthermore, the pH value should be noted when it is given.
27

28
LIFETIME (DAYS)
100000
10000
1000
100
10
1
Water
■■■ 20 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 10 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 5 YEARS ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
■■■ 1 YEAR ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
120 110 100 90 80 70 80 50 40 30 20
TEMPERATURE ( °C)
Chemical Liquid base Functions Compatibility class
oxypropylated and/or oxyethylated hydrocarbon demulsifier < water
alkylphenols “non ionic surfactants” water/glycol
ethylene oxide/propylene oxide copolymers hydrocarbon demulsifier < water
glycol esters hydrocarbon demulsifier < water
fatty amines hydrocarbon corrosion inhibitor class 1
water
water/glycol
imidazoline derivatives hydrocarbon corrosion inhibitor class 1
water
water/glycol
sulphite derivatives water corrosion inhibitor class 1
water/glycol
bisulphite salts water oxygen scavenger class 2
quaternary ammonium salts, water
“quats”, ammonium salts water/glycol biocides < water
aldehydes water biocides class 2
water/glycol
polyacrylates water paraffine inhibitors class 1
water/glycol scale inhibitors
organic phosphonates water scale inhibitors class 3
water/glycol corrosion inhibitors
organic sulfonates water scale inhibitors class 3
water/glycol corrosion inhibitors
hydrochloric acid, 15% water well stimulation class 4
hydrofluoric acid, 15% water well stimulation class 4
The sign “< water” means that the chemical is less agressive than water.
Class 1 Class 2 Class 3
Class 4
Fig. 16 Overview: compatibility
between PA11 grades BESNO
P40 TLO, TL and TLX and different
chemical classes

3.9 Compatibility with crude oil,
natural gas, carbon dioxide (CO 2 )
and hydrogen sulfide (H 2 S)
3.9.1 Compatibility with crude oil
Polyamide 11 is not chemically attacked
by hydrocarbons. Aliphatic hydrocarbons
have a very low solubility in polyamide
11, so that barrier properties are very
high. Low molecular weight aromatic
hydrocarbons can lead to some swelling
at higher temperatures as shown in the
following table.
The low solubility of hydrocarbons and
the high cohesive energy of polyamide
11 result in an excellent blistering
resistance (see section 3.11).
Whereas polyamide 11 is highly resistant
to hydrocarbons, certain other constituents
of crude oil can lead to performance
limitations. These constituents are
water, organic acids, often referred to as
naphthenic acids, carbon dioxide and, to
a lesser extent, hydrogen sulfide. All
these chemicals create different acidities
depending on pressure, concentration
and overall fluid composition. Their
effects are described in the corresponding
chapters.
3.9.2 Compatibility with natural gas
Polyamide 11 is perfectly resistant to
methane, ethane, propane and butane as
well as higher hydrocarbons. Chemical
degradation can only be induced by acid
species, that is carbon dioxide and/or
hydrogen sulfide in combination with
water vapor.
The following test demonstrates the
chemical resistance:
Sheets of BESNO P40 TL with 2mm
thickness are immersed in natural gas at
100°C and 120 bar pressure for a given
time. Mechanical properties are checked.
Composition of the natural gas: 93%
hydrocarbon, 4% hydrogen sulfide, and
3% carbon dioxide and moisture.
Solvent Swelling at 20°C in % weight Compatibility
Benzene 7.5 good up to 70°C / swelling
Toluene 7 good up to 90°C / swelling
Cyclohexane 1 good
Petrol ether 1.5 good
Decaline < 1 good
Gasoline depends on type, mostly < 2% good
Kerosene depends on type, mostly < 2% good
Time Flexural modulus Yield strength Elongation Stress at rupture
(hours) (MPa) (MPa) at break (%) (MPa)
ELONGATION AT BREAK (%)
0 350 27 325 45
100 350 32.5 345 53
250 500 30.5 325 57
500 600 34.5 375 60.5
1000 400 28 360 63
2000 480 32 335 43
5000 460 34.5 430 55
Fig. 17 Polyamide 11, BESNO TL in natural gas - Evolution of elongation at break
500
450
400
350
300
250
200
150
100
50
• • •
0
• •
CRUDE OIL EXPOSURE
METHANE OR NATURAL GAS EXPOSURE AT 20° C
•
1000 2000 3000 4000 5000 6000
TIME (HOURS)
•
29

30
No chemical degradation was observed. Fluctuations in the
mechanical properties are caused by the loss of plasticizer and
changes in moisture content of the gas.
In a typical field experience, polyamide 11 grade BESNO P40 TL
used as a lining for carbon steel pipe was aged in the following
conditions:
Temperature: 65°C
Natural gas: moist, with some condensate, H2S 17%, pH 5.5.
A sample was retrieved after 5 years of service. A chemical
analysis revealed no polymer degradation. Of the initial plasticizer,
30% was lost.
As a conclusion, polyamide 11 grades BESNO TL, BESNO P40 TL,
BESNO P40 TLX and BESNO P40 TLO are compatible with hydrogen
sulfide.
3.9.3. Compatibility with carbon dioxide (CO2)
Polyamide 11 is quite resistant to dry carbon dioxide. However,
carbonic acid formed by dissolution of carbon dioxide in water
under pressure can lead to chain degradation due to hydrolysis.
The rate of hydrolysis, as a function of acidity, is relatively well
known and described in section 3.5.
3.9.4. Compatibility with hydrogen sulfide (H2S)
Polyamide 11 is also resistant to hydrogen sulfide. As with carbon
dioxide, only aqueous solutions which are acidic can lead to
chain degradation. Due to the low acidity and generally low partial
pressures of hydrogen sulfide in crude oil or natural gas,
degradation via hydrolysis seldom occurs.
For a series of tests, please refer to the preceeding section 3.9.2
“Compatibility with natural gas.”
TABLE COMPARING INITIAL AND AGED MECHANICAL PROPERTIES
Elongation Stress at Stress at Elongation at Tensile
at break (%) rupture (Mpa) yield (Mpa) yield (%) modulus (Gpa)
Aged sample 315 ± 38 46.7 ± 8,3 27.7 ± 0.5 42.4 ± 0.6 2.82 ± 0.02
Initial sample 359 ± 48 42.0 ± 3,0 – – 2.78 ± 0.008
3.10 Data on permeability of polyamide 11
The following data were obtained from a detailed study on 6 mm
extruded sheet.
RILSAN ® BESNO P40 TL
P (bar) T (°C) Permeability Diffusion Solubility
/f (bar) cm 3 .cm/cm 2 .s.bar cm 2 /s cm 3 /cm 3 .bar
10 -8 10 -7
CH4 96 99 3.8 7.3 0.05
99 99 4.4 6.1 0.07
103 78 2 2.8 0.07
97 80 2 3.3 0.06
101 61 0.8 2.6 0.03
103 61 0.9 2.2 0.04
102 41 0.4
101 60 0.8 2.2 0.03
CO2 40 79 10 4.5 0.22
39 80 9.4 4.7 0.2
39 60 4.5 1.9 0.23
39 61 4.4 2.3 0.19
41 41 1.5 0.9 0.16
H2S 100/47.5 80 67 7.6 0.88
103/48 80 66 8.2 0.8
92/47 80 77 9.2 0.84
41/33 80 43 4.2 1.04
40/33 80 46 5.1 0.9
39/33 80 38 4.5 0.85

Complementary data can be obtained from the literature.
PLASTICIZED POLYAMIDE 11
Fluid Conditions Permeation value/
cm3.cm/cm2.s.bar CH4 70°C, 100 bars 9x10 -9
CO2 70°C, 100 bars 50x10 -9
H2O 70°C, 50 to 100 bars 2x10 -6 to 7x10 -6
H2S 70°C, 100 bars 1.5x10 -7
METHANOL 23°C, 1 bar 3.7x10 -9
data from IFP/ COFLEXIP OTC 5231
PLASTICIZED POLYAMIDE 11
Fluid Permeation value/cm3.cm/cm2.s.bar 70°C, 25 bar 70°C, 50 bar 70°C, 75 bar 70°C, 100 bar
CH4 0.53x10 -7 1.4x10 -7 1.9x10 -7 1.8x10 -7
CO2 2.3x10 -7 5.8x10 -7 7.8x10 -7 7.8x10 -7
H2O 3.6x10 -6 6.5x10 -6 3.4x10 -6 1.9x10 -6
data from NACE publication, Jan Ivar Skar (Norsk Hydro)
Some differences exist in reported values which can be
explained by different conditioning of the measured samples. For
example, some plasticizer loss leads to high barrier and lower
permeation.
3.11. Blistering resistance
The blistering resistance of a polymer material is directly related
to the solubility of gases in the material and its cohesive
strength. The blistering effect has its origin in the gas bubbles
formed when gas dissolved in the polymer material under high
pressure is expelled on a rapid decompression.
An extensive study has been performed at IFP (French Petroleum
Institute) which confirms the excellent blister resistance of
plasticized polyamide 11 according to the procedures outlined
in API 17J.
The following grades were tested on samples cut from an
extruded pipe, thickness 8 mm:
BESNO P40 TLX
BESNO P40 TLOS
Test conditions:
medium: 85% CH4 + 15% CO2
temperature: 90°C
pressure: 1000 bar
The decompression rate was explosive. The soak time was more
than 30 hours.
Result:
After 20 pressure/decompression cycles, no blister was
observed.
The same result is obtained when the samples were
preconditioned in oil or diesel fuel.
31

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