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ASME B31.3 - Substantive Changes to 2014 Edition

ASME B31.3 - Substantive Changes to 2014 Edition

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 2014 Edition of ASME B31.3, Process Piping.

These changes are:

Category M Fluid Service

The definition was revised in the 2014 edition to provide better guidance on selection of the Category M Fluid Service designation

(b) Category M Fluid Service:  A fluid service in which all of the following apply:

(1) The fluid is so highly toxic that a single exposure to a very small quantity of the fluid caused by leakage, can produce serious irreversible harm to persons on breathing or bodily contact, even when prompt restorative measures are taken; and

(2) If after consideration of piping design, experience, service conditions, and location, the Owner determines that the requirements for Normal Fluid Service do not sufficiently provide the leak tightness required to protect personnel from exposure.

Flared laps are prohibited for use in Category M fluid service in the 2014 edition.

Allowable Stress Range

The 2014 edition explicitly requires that the maximum value of SL considering all conditions be used in calculating the allowable stress range.

Thermowells

The 2014 edition requires that thermowells comply with ASME PTC 19.3 TW.

Cold Spring

The 2014 edition requires that when cold spring is used, the reactions be computed both with the assumption that only two-thirds of the design cold spring is present, and with four-thirds of the design cold spring present.

Impact Testing of Carbon Steels

The 2014 edition restricted the use of Fig.  323.2.2B to provide a further basis for the use of carbon steels without impact testing.  It may not be used for:

  • Piping in elevated temperature service
  • Piping that is expected to experience shock loading or thermal bowing
  • Piping that contains welds between dissimilar materials

The Code warns that the calculation of stresses due to cold springing or misalignment should be included as part of the stress ratio.

Weldolets

The 2014 edition added requirements for and illustrations of welds for integrally reinforced branch connections.

Preheat

The 2014 edition revised the preheat requirements somewhat.  This revision, along with revisions to ASME B31.1, makes the preheat requirements in the two Codes the same.

Heat Treatment

The 2014 edition significantly revised the heat treatment requirements.  This revision, along with significant revisions to ASME B31.1, makes the heat treatment requirements in the two Codes the same.

Examination Personnel

The 2014 edition added specific examination personnel qualification requirements, which are those described in ASME B&PV Code, Section V.  The qualifications:

  • Shall be in accordance with the employer’s written practice and
  • Must be in accordance with one of the following documents
  • SNT-TC-1A, Personnel Qualification and Certification in Nondestructive Testing
  • ANSI/ASNT CP-189, ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel

National or international central certification programs, such as the ASNT Central Certification Program (ACCP) or ISO 9712:2012-based programs, may be alternatively used to fulfill the training, experience, and examination requirements of the documents listed above.

Magnetic Particle and Liquid Penetrant Examinations

The 2014 edition added specific acceptance criteria for magnetic particle and liquid penetrant examination.

Hydrotest

  • The 2014 edition permits the hydrotest pressure to be lowered to the design pressure while examining for leaks.
  • The 2014 edition simplified the calculation of hydrotest pressure.

High Pressure Piping

The 2014 edition changed the leak test pressure from 1.5 times the design pressure corrected for temperature to 1.25 times the design pressure corrected for temperature.

Alternative Rules for Evaluating Stress Range

Because of the potential for misapplication of the alternative rules, and because many of the provisions of Appendix P had been incorporated into the base Code, Appendix P was removed in the 2014 edition.

 

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Comments 26

Don Frikken on Sunday, 15 March 2015 11:21
RE:Use of Maximum value of SL in Allowable Stress Range

I’m not sure I understand your question, but I will try an explanation and you can ask again if what I say does not help.

SL for use in this equation is normally caulated using just weight and pressure loads. Occasional loads such as wind, earthquake and water hammer are normally excluded. SL can vary when the piping is alternately filled with liquid and gas, and it can vary when the piping grows up off of a support in the hot condition. In my opinion, the Code now requires that you calculate the maximum value of SL for all of these expected condition, and use that value when you calculate SA.

I’m not sure I understand your question, but I will try an explanation and you can ask again if what I say does not help. SL for use in this equation is normally caulated using just weight and pressure loads. Occasional loads such as wind, earthquake and water hammer are normally excluded. SL can vary when the piping is alternately filled with liquid and gas, and it can vary when the piping grows up off of a support in the hot condition. In my opinion, the Code now requires that you calculate the maximum value of SL for all of these expected condition, and use that value when you calculate SA.
Guest - M. Mistry on Tuesday, 17 March 2015 02:26
RE:RE:Use of Maximum value of SL in Allowable Stress Range

Thanks for your prompt response.
Your explanation is definitely going to help. But I would have further more questions;
Up till now we had evaluated SL using just weight and pressure loads and compared w.r.t. Sh (Hot Allowable stresses).
Like in similar manner whether hot sustained SL (when the piping grows up off of a support in hot condition) needs to calculate first and to be compared with SA (Thermal Allowable stress range) or Sh (Hot Allowable stresses) prior to use in Liberal Allowable limits as SLmax?

Thanks for your prompt response. Your explanation is definitely going to help. But I would have further more questions; Up till now we had evaluated SL using just weight and pressure loads and compared w.r.t. Sh (Hot Allowable stresses). Like in similar manner whether hot sustained SL (when the piping grows up off of a support in hot condition) needs to calculate first and to be compared with SA (Thermal Allowable stress range) or Sh (Hot Allowable stresses) prior to use in Liberal Allowable limits as SLmax?
Don Frikken on Saturday, 28 March 2015 11:08
RE:RE:RE:Use of Maximum value of SL in Allowable Stress Range

When we did these calculations using less sophisticated methods than are available today with the various computer programs, we did calculated SL first, then we calculated SA, then calculated SE. The use of the “conservative” allowable stress range became popular because it simplified the calculation of SA and we could evaluate SL and SE separately. With today’s computer programs, SL, SA and SE are calculated at the same time at every point in the piping system. The complicating factor with the new requirement is that a single case (weight + pressure + thermal + displacement) for the maximum SL and the maximum SE must be input in order to get a complete picture from the computer program output when using the “liberal” allowable stress range.

When we did these calculations using less sophisticated methods than are available today with the various computer programs, we did calculated SL first, then we calculated SA, then calculated SE. The use of the “conservative” allowable stress range became popular because it simplified the calculation of SA and we could evaluate SL and SE separately. With today’s computer programs, SL, SA and SE are calculated at the same time at every point in the piping system. The complicating factor with the new requirement is that a single case (weight + pressure + thermal + displacement) for the maximum SL and the maximum SE must be input in order to get a complete picture from the computer program output when using the “liberal” allowable stress range.
Guest - MJ on Friday, 08 June 2018 14:23
Thermal Shock Load Definition

Hi Don,

If my flare header (SA333) metal temperature becomes colder from amb. temp (e.g. 0C or -45C) to -45 in 30 to 40 seconds, is this a thermal shock?

What is the exact definition of thermal shock?


Thanks
MJ

Hi Don, If my flare header (SA333) metal temperature becomes colder from amb. temp (e.g. 0C or -45C) to -45 in 30 to 40 seconds, is this a thermal shock? What is the exact definition of thermal shock? Thanks MJ
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