×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Welding and PWHT Valves into Pipe Lines

Welding and PWHT Valves into Pipe Lines

Welding and PWHT Valves into Pipe Lines

(OP)
What is the prefered position the valve should be in, when welding and PWHT of the butt welds to piping, should it be open, closed or somwhere between? my main concern is for Alloy like P5A & P5B.
Is there any backup information, and where can I find it.

RE: Welding and PWHT Valves into Pipe Lines

The valve manufacturer is the best one to ask.

In general, I can think of two concerns during welding and PWHT: (1) Weld splatter could cause damage. This is to be avoided by putting the valve in the position where the least damage can occur e.g. if it is a ball valve, keep it in the open position, and mask off the exposed portion of the seating area. (2) Heat could damage the soft seals and inserts, if any. Normally the manufacturer will provide a sufficient length for the BW ends to avoid this problem. Please see other threads in this forum for discussions on this topic.

However, I could not think of a possible relationship between the type of material (P5A, P5B) with the position of the valve. Can you clarify?

RE: Welding and PWHT Valves into Pipe Lines

The short-version answer is 'fully open'. For gate and globe valves you want to fully backseat the valve.

RE: Welding and PWHT Valves into Pipe Lines

Rule of thumb from my experience is "partially" open.  Check manufacturer's installation and maintenance manual for specifics.

JN

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources