Sunday, April 28, 2013

[MW:17579] Pre heat requirements for tack welding in P91

Dear Experts,

 

Regarding the subject mentioned, kindly clarify my following doubts.

(a)    Preheating required for P91 as per B 31.1 is 200°C (mini). Does it mean that this Pre heat shall be given for tacking also.

(b)   PWHT holding time for P91 mentioned in B 31.1 is 1 hr/25 mm; minimum 30 minutes. Does it mean that if the thickness is 6/10/12.5 mm the holding time is 30 minutes & for 15 ,20,30,40 mm the holding time is 36  48,72,96 minutes respectively.

(c)    I got some special heating curves for P 91 from our group. But Kindly explain about the reference /standard used for preparation of this heat curve ( eg- why the preheat maintenance is 4 hours & again free cooling).

 

S.Binoy

 

 

By -

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Re: [MW:34874] ASME IX, groove weld during WQT limits for Fillet Weld production

Hi David,  There are two points in WQT. 1. Thickness of Base Metal -T 2. Thickness of Weld Metal -t When you use a combination of two proces...

  • Materails FAQs
    Q: What are equivalents for standard Q 235 B (and Q 235 A) for U-channels? ...
  • RE: [MW:5585] Buttering of weld joints
    Definition of buttering from ASME Section IX, QW/QB-492 Definitions:   Buttering:  the addition of material, by welding, on one or bot...
  • WELD AND WELDING SYMBOLS
    Section I. PRINT READING 3-1. GENERAL a. Drawings . Drawing or sketching is a universal language used to convey all necessary information to...