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Changes In the 2012 Edition of ASME B31.3

In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2012 Edition of ASME B31.3, Process Piping. These changes are:

Category D Fluid Service

The definition was revised to include piping with design minimum temperatures below -29⁰C (-20⁰F) if the cause of the lower temperature is from ambient conditions.

Allowable Displacement Stress Range

The allowable displacement stress range was limited to 60,000 psi (414 MPa) in the 2012 edition. High strength steels have higher yield and tensile strengths and thus higher allowable stresses. Therefore, they also have higher calculated allowable displacement stress ranges when calculated using the old formula. However, these materials have fatigue strengths similar to the more common steels, which is why the limit was added.

Flexibility Stress Equation

The axial stress was added to the flexibility stress equation. While axial stress in not important in most piping systems, it can be important for piping that is jacketed or buried. The 2010 edition required that it be considered, but it was not in the equation.

Welding Qualification

Restrictions to acceptance of previously qualified welding procedures were removed. Specific language about use of standard welding procedures as permitted by ASME BPV Code, Section IX was added.

Preheating

The 2012 edition changed "recommended" preheat temperatures to "required" preheat temperatures. All metals must now be preheated to 10⁰C (50⁰F) or higher before welding.

Owner's Inspector

The qualification requirements for an Owner's Inspector were broadened in the 2012 Edition.

MPa Stress Table

The MPa allowable stress table first appears in the print version in the 2012 edition. This table is still just for information. The psi allowable stress values are the requirement.

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Comments 18

Guest - Jayaprakash on Friday, 08 March 2019 09:17
Summary of substantial changes to ASME B 31.3 since 2004 edition

Hi Don,

Appreciate your efforts in providing these useful information. Do you have a summary of all the substantial changes to ASME B 31.3 since 2004 edition all the way up to 2016 edition? It would be a great help as we are planning to use the latest edition of this code for a project, however the regulation still list 2004 edition.

Hi Don, Appreciate your efforts in providing these useful information. Do you have a summary of all the substantial changes to ASME B 31.3 since 2004 edition all the way up to 2016 edition? It would be a great help as we are planning to use the latest edition of this code for a project, however the regulation still list 2004 edition.
Don Frikken on Friday, 08 March 2019 09:48
Summary of substantial changes to ASME B 31.3 since 2004

Yes, I can provide that. Just send me an email request at dfrikken@becht.com.

Yes, I can provide that. Just send me an email request at dfrikken@becht.com.
Guest - sharu on Wednesday, 29 April 2015 02:09
Allowable Displacement Stress Range

Dear Sir,
Regarding the statement.
"The allowable displacement stress range was limited to 60,000 psi (414 MPa) in the 2012 edition. High strength steels have higher yield and tensile strengths and thus higher allowable stresses. Therefore, they also have higher calculated allowable displacement stress ranges when calculated using the old formula. However, these materials have fatigue strengths similar to the more common steels, which is why the limit was added."

My doubt is Sc and Sh was limited to
a maximum of 138 MPa (20 ksi) when using a
value of f > 1.0 in 2010 edition itself. Then why did you mentioned this point in the changes occurred in 2012 edition.

Please Clarify

Dear Sir, Regarding the statement. "The allowable displacement stress range was limited to 60,000 psi (414 MPa) in the 2012 edition. High strength steels have higher yield and tensile strengths and thus higher allowable stresses. Therefore, they also have higher calculated allowable displacement stress ranges when calculated using the old formula. However, these materials have fatigue strengths similar to the more common steels, which is why the limit was added." My doubt is Sc and Sh was limited to a maximum of 138 MPa (20 ksi) when using a value of f > 1.0 in 2010 edition itself. Then why did you mentioned this point in the changes occurred in 2012 edition. Please Clarify
Don Frikken on Sunday, 03 May 2015 09:03
RE:Allowable Displacement Stress Range

Limiting Sc and Sh to 138 MPa applies no matter what the value of f is. Without this limit, the allowable stress range could be higher than 414 MPa for high strength steels when f = 1.0 or less. For example, SA could be as high as 617 MPa for X80 material.

Limiting Sc and Sh to 138 MPa applies no matter what the value of f is. Without this limit, the allowable stress range could be higher than 414 MPa for high strength steels when f = 1.0 or less. For example, SA could be as high as 617 MPa for X80 material.
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