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Participant

Join Date: Dec 2011
Posts: 1

Blowdown Valve Failure

09/27/2013 11:48 AM

Recently in one of our FPSO during the routine maintenance at annual shutdown it was found that 6 nos. of blowdown valves were not working properly. Valves are stuck in close position and are not opening. Further investigation revealed two important points:
1. All these valves are floating ball valves;
2. Actual torque required to open the valves are very much higher than the designed torque - it is almost more than double of the design torque.

Most of the line sizes are 2" to 3" and pressure rating 600#. Valves are operating fine when there is no DP across the valve. Question is what could be the reason for this increase of torque and failure? Normally for bigger line sizes we use Trunnion mounted valves. Have other people in the industry also faced the same problem with floating ball valves? I checked the BP and SHELL spec. Both of these reputed company specs. suggests to use Trunnion mounted ball valves only for shutdown/blowdown application.
Any experience/feedback from the professionals in this forum will be very helpful in this matter.

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Guru

Join Date: Oct 2008
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#1

Re: Blowdown valve failure

09/27/2013 12:08 PM

You've already heard from two vendors who should know.

This may be a dumb question, but what does your safety engineer and insurance company say about your 6 failed valves????????????????????

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Guru

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#2

Re: Blowdown Valve Failure

09/27/2013 7:24 PM

A. The problem wasn't detected until shutdown?

B. Has the actuator sizing been checked?

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Guru
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#3

Re: Blowdown Valve Failure

09/28/2013 6:26 AM

<deleted> nevermind.

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Guru
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#4

Re: Blowdown Valve Failure

09/28/2013 2:45 PM

Why weren't these valves cycled daily?

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Guru
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#5

Re: Blowdown Valve Failure

09/28/2013 3:49 PM

What is the blowdown regime on these boilers?

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