Prior to 2014, ASME B31.3 required carbon steel welds be post weld heat treated (PWHT). However, with recent amendments of this Code allowing exemptions when weld thickness exceeds certain limits, post weld heat treatment becomes optional in certain instances. This paper will analyze the arguments used to justify exemptions, showing many to be invalid or incomplete. Furthermore, an EPC contractor’s perspective will also be provided along with practical approaches that may help mitigate risks. PWHT Requirements PWHT of carbon steel can be an expensive and complex process, yet there has been growing interest in eliminating its requirement from fabrication standards for certain applications. This trend can particularly be found within …

続きを読む “Comparison of ASME B31 3 PWHT Requirements”

The B31.3 Code defines rules for piping systems used in oil refineries, chemical, paper & pulp, semiconductor manufacturing facilities, power generation stations and similar processing plants. This document specifies requirements for designing, fabricating, assembly erection examination inspection & testing of process piping. An EPRI report (Ref 1) has recommended that the PWHT temperature for 1-1/4 Cr materials should be reduced, and this report will support that change within B31.1 and B31.3 codes. 1. PWHT Temperature Range Different codes governing pressure vessels and piping vary considerably on various issues, including required PWHT temperatures. Most differences arise due to industry traditions rather than specific metallurgical or structural considerations; as a result, attaining …

続きを読む “B31.3 PWHT Table”

Post-weld heat treatment (PWHT), commonly referred to as stress relief, involves heating and cooling welds to alleviate residual stresses that could otherwise lead to cracking and fractured welds. PWHT involves specific rates, tolerances and times at temperature that Wisconsin Oven furnaces offer for maximum stress-relief. Annealing, normalizing and stress relieving are just some of its applications for PWHT treatments. Process Post weld heat treatment (PWHT), commonly referred to as stress relief heat treatment, tempers the metal and reduces residual stresses caused by welding, thus decreasing fatigue cracking rates and increasing resistance against brittle fracture. PWHT is an essential step in maintaining integrity for structures or equipment exposed to dynamic loads. …

続きを読む “A Qualified PWHT Company Is Essential For Your Project”

Since 2014’s edition of ASME B31.3, thick carbon steel pipe has been exempted from post weld heat treatment (PWHT) requirements with only multi-pass welding required and no preheat requirement necessary. There have been concerns raised that such exemptions may be unsafe. This paper, sponsored by EPRI and written by RRAC team members, is intended to support changes to minimum PWHT temperature requirements of B31.1 and B31.3 codes as well as similar changes elsewhere in codes. Minimum Preheat Temperature ASME B31.3’s minimum preheat temperature requirements differ significantly across codes and standards, possibly reflecting different service conditions addressed by each standard or code. Real concerns emerge when requirements of one code or …

続きを読む “ASME B31.3 Post Weld Heat Treatment Requirements For Carbon Steel Pipe”

This week marked the debut of the Professional Women’s Hockey League season and its rules will differ significantly from those seen in the National Hockey League (NHL). While teams in NHL receive two points for winning an overtime or shootout game, while in PWHL they only get credit if their victory came during regulation time. Jailbreak Goals Professional Women’s Hockey League (PWHL) fans have taken notice of a unique rule known as a jailbreak goal that allows a player serving a penalty to be released if her team scores a shorthanded goal during her penalty session. It adds a level of excitement and anticipation during games this season; Erin Brown …

続きを読む “The Shootout and Jailbreak Goal in PWHL Hockey”

ASME Section VIII, Division 1 is an important engineering standard that provides clear guidelines for creating, inspecting, and certifying pressure vessels. This contributes to standard engineering practices while improving safety and efficiencies across different industries. Post weld heat treatment (PWHT) is a controlled process designed to eliminate residual stresses in welded materials and is defined in clause 331.11 along with tables 331.1.1.1 and 331.1.3. It must comply with requirements set out by clause 331.11.1.2 as set out below for piping applications. Minimum Temperature Post Weld Heat Treatment (PWHT) involves heating weld metal to temperatures below its lower critical transformation temperature and holding for an extended period. This helps reduce residual …

続きを読む “Post Weld Heat Treatment (PWHT) Requirements As Per ASME Section VIII, Division 1”

ASME Section VIII contains comprehensive requirements for the design, fabrication, inspection, testing and certification of fired or unfired pressure vessels with internal or external operating pressures exceeding 15 psig. In addition, this standard provides mandatory and nonmandatory appendices that detail additional design criteria, nondestructive examination standards and acceptance standards that apply. Division 1 As its name implies, Division I of ASME Section VIII code deals specifically with pressure vessels. It specifies the mandatory and nonmandatory construction requirements, along with welding specifications such as WPSs (Welding Procedure Specifications), PQRs, and welder performance qualifications; making certain these documents are correctly documented before placing vessels into service is important. Post-weld heat treatment (PWHT) …

続きを読む “ASME Section VIII Div 2 PWHT Requirements”