ASME B31.4 Fracture Control Program 1

[RobSmith1975]

Hi

I'm writing a report to reinstate a redundant pipeline.. During process studies it has been concluded that the material could experience a minimum design temperature of -42C if the piping is subject to adiabatic flash at atmospheric pressure, this is the fluid boiling at atmospheric pressure taking energy from the atmosphere to provide the heat of vaporisation.

ASME B31.4 Section 423.2.6 Materials for Use in Low-Temperature Applications states “Whenever the minimum design temperature (see para. 401.2.3.7) is below -20 °F (-30 °C), a fracture control program shall be established”

Could anyone offer any advice on what a fracture control program would involve or is there a separate standard/specification that is used for such a program?

Would it be linked to ASME B31T - “Standard Toughness Requirements for Piping”?

Any advice would be greatly appreciated

 

[BigInch]

You'd want to do your testing at, or perhaps slightly lower than, the pipeline's lowest design temperature. That's all that is normally required.

 

[LittleInch]

You really need to get some material specialists involved.

In general like BI says, the test temperature for certain tests like charpy testing and drop weight tests need to be undertaken at or below your min design temperature.

what values you need or are acceptable are dependent on the material.

Using an existing line you are somewhat limited by the data available to you from the original test data on the pipe material. I note you don't actually state what the min design temperature of this existing redundant line was,.....

It is sometimes possible to extrapolate from test temperatures to a new test temperature, but the last time I tried it, it ran into problems as the codes had changed and didn't allow it anymore.

So if your test temperature for your pipe is higher than your new temp of -42C, then its find a new pipe time....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RobSmith1975]

Hi guys

Thanks for the responses.

The minimum design temperature for the line is -5C. However there is the risk when de-energising the line of adiabatic flash.

I'm familiar with the methods and requirements of testing, it was the term "fracture control program" that bothered me as I interpreted that as a continuous series of actions that would need to be employed throughout the life span of the line whilst in service. Have I interpreted it wrong?

 

[LittleInch]

I also think you need to get the latest version of B 31.4 2012 as the section you quote doesn't exist anymore and hasn't moved anywhere else so the term has seemingly become redundant.

Instead they have section 403.7 which lays out a set of basic requirements for criteria to prevent fracture.

I think you're right to be concerned and especially as the min design temperature looks like it needs to be modified and hence your existing pipe is unlikely to meet the new requirements.

A lot will depend on how long this lasts, what the pressure is ( 0 barg?) and how the stress is affected by such a cold temperature.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RobSmith1975]

Hi littleInch

The section I was quoting is from ASME B31.4 - 2016 edition

 

[LittleInch]

OK, that's me going off to the new code store....

sorry...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

Now I've got the new version, I'm not sure what your issue is.

The rest of 423.2.6 spells out what the program involves and a new part of 403.7 references B31T for more information on appropriate toughness.

Your issue I think is what do you set the minimum design temp to be.

given you're using an existing system, but putting something in it which I can only assume is OK (i.e. above -5C) at normal operating, but then flashes off to be a gas at -42C, then it looks to me like you can't use this pipeline for that fluid. What is the fluid out of interest.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RobSmith1975]

I perhaps should have worded my initial post better. I was hoping to find written documentation or an example from someone of a fracture control program already implemented.

The fluid is propane (C3) that is to be transferred between plants at a design pressure of 35 Bar.

There is a redundant line existing between the plants that was originally to be used for crude hydrogen but never put into service. The intent is/was to use this for the propane transfer

 

[LittleInch]

As this is a new section in the 2016 version of 31.4, you might be the first!

I think the term "program" make sit sound more complex than it is actually is. That main section and 403.7 gives a pretty good list of items which need to be included / reviewed / created.

clearly it is designed for new pipelines and not the situation you find yourself in.

From the data you've supplied, it doesn't look to me like the current pipe would survive, at least on paper, an excursion down to minus 42C. Nice try, but unless you can extract a piece of it and re-test it at -42C and it somehow has the right mechanical properties, looks like a new pipe to me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[weldstan]

You need to determine the stress in the pipe at -42 C both due to pressure and contraction due to the delta T.

If stress is very low relative to the SMYS of the pipe, you may very well be able to use the existing line.

 

[SJones]

1. Look at the definition of minimum design temperature and see whether the adiabatic flash scenario meets the definition

2. This is a classic fitness for service exercise usually addressed by, in order of preference: BS 7910; API 579-1/ASME FFS-1. Review the sections on brittle fracture.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[RobSmith1975]

Thanks for all your help guys, much appreciated