• Asme Section Viii Pwht Requirements Specification
• Asme Section Viii Pwht Requirements Section
• Pwht Chart
• Asme Section Viii Pwht Requirements Pdf
• Pwht Requirements As Per Asme Section Viii Div 1

Asme Section Viii Pwht Requirements Specification

Asme Section Viii Pwht Requirements Section

In this video tutorial Manny explains how WeldCode can be used to determine Preheat and PWHT Requirements. Visit for more useful content. Hi sulhal, if it's question of Section VIII-1 HE: T11/F11 are both P-No.4 Gr.No. 1 materials, according to Table UCS-56: PWHT is mandatory. No exceptions in Note b can be applied since the tube-tubesheet weld is not a butt weld.

Pwht Chart

by Murali
(UAE)

Asme Section Viii Pwht Requirements Pdf

Pwht Requirements As Per Asme Section Viii Div 1

What are PWHT requirements in pressure vessel inspections?
Bob's Reply: I prefer to answer to this question in two separate questions as below:
1. When and where PWHT is mandatory by code requirement?
2. How PWHT must be done when it is mandatory?
Pressure Vessel Inspections-Answer to question 1:
If we focus only in ASME Code Section 8 Div 1, there are lots of conditions which cause the PWHT to be mandatory. Some of them are:
a) Based the requirement of UW-2(a) when our service is lethal and our material is carbon steel or low alloy steel.
b) Based the requirement of UW-2(c) when our pressure vessel is unfired steam boiler and our material is carbon steel or low alloy steel.
c) Based the requirement of UW-2(d) when our pressure vessel is subjected to direct firing and our material is carbon steel or low alloy steel.
d) Based the requirement of UCS-56 when our nominal thickness exceeds a specific value, for instance 38 mm for P No.1 material or 0 mm for P No.3 material.
UCS-56 also gives min. PWHT temperature and min. holding time (soaking period) based on P-Nos. and thickness respectively.
e) Similarly to the UCS-56, the same apply for other martial groups i.e. UNF-56, UHA-32, UHT-56 and etc.
f) Based the requirement of UCS-68(b) when our MDMT (Minimum Design Metal Temperature) is below -55 Degree F.
Pressure Vessel Inspections-Answer to question 2:
When one of above requirement applies to us, then we must do PHWT based the requirement of UW-40 which detail to us the PHWT procedure.
Some important requirements in this clause are:
a) For Furnace PWHT, Loading Temperature shall not exceed 800°F, heating rate 400 deg F/hr/inch of thickness, cooling rate 500°F /hr/inch of thickness.
Still air cooling permitted below 800°F. During soaking period, temp difference between hottest and coldest part shall not exceed 150°F.
b) Minimum overlap for PWHT in multiple heats is 5 ft.