×
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

Acceptance criteria for defects on machined areas of valve castings

Acceptance criteria for defects on machined areas of valve castings

Acceptance criteria for defects on machined areas of valve castings

(OP)
Many a times we find surface breaking defects in castings after machining at the valve manufacturer location.

These castings would have been radiographically tested(only critical area as per B16.34) and accepted with 3.2 certification.

What is the acceptance criteria for relevant indications noticed during PT/MPT on machined surfaces of castings?
Is it allowed to repair such defects, revealed by surface NDE after final machining, by welding at valve manufacturer's place? Will it affect the 3.2 certification issued by the foundry and endorsed by TPI?  

RE: Acceptance criteria for defects on machined areas of valve castings


In my opinion (and this is an opinion only): surface repairs will not generally be accepted for 'qualified valves'.

Reasons are several: surface repair will involve cleaning (grinding?)and welding, which again might have weakening effects on larger areas and general structure other than effected. A surface fault could also indicate deeper cracks and faults not found either by machining or radiographics.

If surface defects often (many times?) are found after the valve bodies have passed radigraphic, visual and other tests, this would obviously raise the question of the foundry's general quality level, including all manufacturing and QA procedures and practice.

Some end users excludes in their valve specifications surface defect repaired valves for some or all applications.

Other end users have special requirements for which type of parts/repairs to be accepted, usually with extra documentation and tests requirements, very often including welding procedures, repair procedures requiring among other thing certified welders etc. etc.

For common castings for cheaper-end valves the sensible thing would be to return/not accept any casting fault, but yes, some factories repairs some surface defaults for some valves.

I doubt a general answer can be given without including the end users of the specific valve.

RE: Acceptance criteria for defects on machined areas of valve castings

I agree with gerhardl.....

This is too difficult to say. It depends on the customer, the application, the pressure class, where the defect is, how big it is in terms of surface area but also in terms of the depth of the defect.

If the defect is ever more than 1/4 wall thickness then it should be scrapped as a general rule!

 

RE: Acceptance criteria for defects on machined areas of valve castings

In view of a client, I tend to reject the valve especially for welded repair. However, we have to consider in detail for each specific case.

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