×
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

alloy 800ht

alloy 800ht

alloy 800ht

(OP)
hi,

we have to weld some pipes in this material, with pwht , in my opinion with 875ºc 3 hours is good what do you think?

thaks

RE: alloy 800ht

There is no post weld heat treatment required for this material.

RE: alloy 800ht

(OP)
in the new revision of asme VIII is not necessary??  

RE: alloy 800ht

No. The only requirement for solution treatment is after post bending not welding.

RE: alloy 800ht

(OP)
and stress relief?

RE: alloy 800ht

berrojalbiz;
I am going to correct myself here, per ASME Section VIII, Div 1, UNF-56, 1 (e)

for Incoloy 800,800H, 800HT, these alloys will be subject to PWHT if they are in service above 1000 deg F.

PWHT min 885 deg C for 1.5 hours for thickness up to 1".

If you meet the conditions above, it must be 885 deg C minimum.

Alos, for welding bellows (thin section material), the PWHT does NOT apply.

RE: alloy 800ht

(OP)
operation service is above 1000ºF is the outlet of a hydrogen reformer , the design in the planes said that only need pwht in trunions 875ºC for 3 hours why?? i don´t understand it it could be because of stress concentrations in those points??

thanks a lot

RE: alloy 800ht

berrojalbiz;
If you review the technical data sheet on Alloy 800H/HT by Special Metals, post fabrication strain is either from cold work or from welding (residual stresses). Stress relief is accomplished by the thermal treatment as mentioned above.

http://www.specialmetals.com/products/incoloyalloy800h&ht.php

Review page 10.

RE: alloy 800ht

If this piping is indeed in a steam reformer, the piping will be operating well above 1000 F- in fact, perhaps even above your proposed 885 C PWHT temperature...Does that perhaps help you understand?
 

RE: alloy 800ht

(OP)
yes because if in service is above this temperature we will do the treatment in service .......???

RE: alloy 800ht

Alloy 800Ht is succeptable to relaxation cracking when subjected to secondary stresses at temperatures 1000-1400°F.
For that reason ASME VIII requires PWHT if operating above 1000°F

RE: alloy 800ht

The process is bend/weld, heat treat, then inspect for cracking that might have occurred after your piping went through its first operational thermal cycle.  Much better to find cracks now rather than during commissioning!

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