Is it necessary to install a downhole safety valve in a subsea ... - NTNU
Is it necessary to install a downhole safety valve in a subsea ... - NTNU
Is it necessary to install a downhole safety valve in a subsea ... - NTNU
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Reliabil<strong>it</strong>y data dossier<br />
Component: Swab <strong>valve</strong>, annulus swab <strong>valve</strong>, annulus w<strong>in</strong>g <strong>valve</strong> and crossover <strong>valve</strong><br />
Failure rate<br />
(10 -6 /hours)<br />
Failure mode<br />
Data source/comment<br />
4.57 All All failures of gate <strong>valve</strong>s are<br />
calculated w<strong>it</strong>h a MTBF of 25 years,<br />
personal conversation w<strong>it</strong>h Marv<strong>in</strong><br />
Rausand [19].<br />
2.23<br />
1.67<br />
LCP: 21.76%<br />
ITL: 14.74%<br />
EXL: 12.26%<br />
=48.70%<br />
LCP: 21.76%<br />
ITL: 14.74%<br />
=36.50%<br />
0.56 EXL: 12.26%<br />
Recommended values for calculations:<br />
Failure rate (10 -6 /hrs):<br />
LCP, ITL, EXL: 2.2<br />
LCP, ITL: 1.7<br />
EXL: 0.6<br />
Test<strong>in</strong>g and ma<strong>in</strong>tenance:<br />
The <strong>valve</strong>s are not tested. A well workover is required for replacement.<br />
Failures regard<strong>in</strong>g leakage through<br />
the <strong>valve</strong>s and external leakage.<br />
The distribution of failure modes is<br />
accord<strong>in</strong>g <strong>to</strong> those of gate <strong>valve</strong>s<br />
<strong>in</strong> OREDA 97, p 348.<br />
Failures regard<strong>in</strong>g leakage through<br />
the <strong>valve</strong>s. The distribution of<br />
failure modes is accord<strong>in</strong>g <strong>to</strong> those<br />
of gate <strong>valve</strong>s <strong>in</strong> OREDA 97, p 348.<br />
Failures regard<strong>in</strong>g leakage <strong>to</strong> the<br />
surround<strong>in</strong>gs. The distribution of<br />
failure modes is accord<strong>in</strong>g <strong>to</strong> those<br />
of gate <strong>valve</strong>s <strong>in</strong> OREDA 97, p 348.<br />
Comments and leakage paths:<br />
The external leakage of these <strong>valve</strong>s is through the material, actua<strong>to</strong>r or seals and <strong>to</strong> the<br />
surround<strong>in</strong>gs. Internal leakage goes thru the <strong>valve</strong>.<br />
D-7
Change language