Again About Washers in subsea application

[JohnLL]

There was a thread in this forum about "using washers in subsea bolted connections" (thread311-296001).
It was suggested there that no washers are usually used in subsea applications. But why?
As washers are required to provide larger pressure area, avoid component (let's assume flanges) damage during fastening, etc. Why we should not use them? and if we don't, how we handle these problems which could not be tackled onshore without washers?

 

[TVP]

In order to obtain the benefits of washers, they are usually heat treated steel, which is susceptible to environment assisted craving (SCC, hydrogen embrittlement, etc.). Thick flanges and relatively low strength bolts reduce the need for high preload in the joint, which also reduces the necessity for washers.

 

[MikeHalloran]

One thing I had not considered until Macondo blew: Try to manipulate washers with a robot.



Mike Halloran
Pembroke Pines, FL, USA

 

[BigInch]

I was going to mention the bit about fooling around with washers under water. Even for a human, underwater "it ain't easy". Also washers tightened at surface pressures, against surfaces that move closer together at very high pressures anyway only offer just one more source of slack in the bolt line up.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso