Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF : RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
STANDARD SPECIFICATION
TITLE WELDING OF ONSHORE GAS
SPECIFICATION NO. PAGE 33 OF 48
PIPELINES
MEC/S/05/62/02 REVISION
16.3.13 COMPANY shall have free access to all the CONTRACTOR's work facilities in
the field.
16.3.14 Any approval granted by the COMPANY shall not relieve the CONTRACTOR of
his responsibilities and guarantees.
16.4 Radiation Source
16.4.1 Radiographic examination shall be carried out using x-radiations, Radiographic
examination by Gamma rays may be allowed, at the discretion of the
COMPANY, in case of inaccessible joints. Radiography by Gamma-Ray for tie-in
joints shall be acceptable provided Du AGFA film or equivalent is used and the
reqd. sensitivity obtained. Radiography by Gamma-Ray for tie-in-joints shall be
acceptable provided D4 AGFA film or equivalent is used and the required
sensitivity obtained.
16.4.2 Whenever possible, pipeline welds will be inspected by placing the radiation
source inside the pipe, on the pipeline axis, with a radiation of 6.28 rad. (360°C).
If it is impossible to place the radiation source inside the pipe, the weld will be
inspected with the source on the outside. An overlap of at least 40mm at the
ends of each film shall be required to ensure that the first and last location
increment numbers are common to successive films and to establish that no part
of a weld has been omitted.
16.5 Level of Quality
The quality level of Radiographic sensitivity required for radiographic inspection
shall be at least equivalent to the values in Fig. 6
16.6 Penetrameters
The image quality indicator (abbreviation : IQI) shall be used for the qualification
of the welding procedure and during normal line production. Radiographic
sensitivity shall be measured with the wire image quality indicator
(Penetrameter). The penetrameter shall be selected according to DIN54109 ro
ISO1027. For radiographs made with the source on the outside, a penetrameter
shall be placed on each side of the film with the smaller wiere of the
penetrameter turned towards the end of the film itself. When a complete weld is
radiographed in a single exposure using a source inside the piping, four
penetrameter approximately equally spaced around the circumference shall be
used. During the procedure qualification, IQI shall be placed both on the source
side and on the film side. The sensitivity obtained with IQI on the source side
shall not be less than the values shown in Fig. 6 of this specification.
\\Akjha\work contrac\standard TS for Pipe Line WC (Vol-II) MASTER FOLDER\02A welding onshore gas pipeline\Welding of Onshore Gas Pipelines with addendum - I 02A.doc