ASTM A-106 FOR PROPANE-PROPYLENE SERVICE 2

[Lebpower]

Good day,

I'm designing a new pipeline system using DEP SHELL piping class for Propane+Propylene service, they recommend to use ASTM A-333.

Is there any bad experience using ASTM A-106 Gr. B in this type of service?

I'm assuming that ASTM A-333 is recommended due to the cryogenic tempeture of the propylene.

Any thoughts about this?

 

[DGrayPPD]

ASTM A333 is the standard specification for seamless and welded steel pipe for low-temp service.
ASTM A106 is the standard specification for seamless carbon steel pipe for high temp service.

What is the design temp for this service?

There are some minor differences in the material chemical composition, mechanical properties, and heat treatment as you can see here...

http://www.shew-esteelpipe.com/news/the-difference-between-a333-gr-6-and-a106-gr-b-5716785.html

My recommendation would be to just follow the DEPs. If the service temp is cryogenic then yes that would be the main reason for specifying ASTM A333.

I'm sure wiser and more experienced professionals will be along soon to give more insight.

 

[Ehzin]

Yeah, I see this is just a temperature issue. The listed metallurgy shouldn't have any effect considering it's just propane/propylene. As a side note, even propane could have temperature issues during depressuring events albeit not as severe as propylene.

Thanks,
Ehzin

 

[MJCronin]

The maximum and minimum design temperatures also affect the selection of the flange type, gaskets and bolting materials as well as valve types and valve operators.

What is the minimum design temperature for your system ?

ASTM A106-GRB carbon steel piping material is only used to -20F . A333 was developed specifically for low temperature service.

Are you working in accordance with P&IDs developed by a competent chemical engineer ? P&IDs should be specifying the types of materials used in various system.

MJCronin
Sr. Process Engineer

 

[Lebpower]

Good Morning,

Thank you all for your quick responses.

Design Temp= -50ºC / -58F
Design P= 38.3 Kgf/cm2 / 545Psi

Giving the fact that ASTM A-106 Gr. B is only used until -20F, it's clear that I can´t use this material as an alternative instead of A333.

After your responses I am much more clear about the differences between those materials, also I just did a deep look into the P&ID and in all the PP system is recommended A333.


Now I got another question:

How this temperature affect the selection of the valve type?



Thank you again.

 

[Ehzin]

You'll have the same question regarding metallurgy. Can my valve body handle these lowered temperatures without possibly leading to brittle fracture. The second question you'll run into a bit more specific to valves is are there internal soft goods, e.g. seats, o-rings, and gaskets that have their own issues at low temperatures. O-rings could lose some "ductility" (Pretty sure poor word choice) as in not spring back when loads on them change and lead to leakage. When it comes to the valves I would confer with prospective valve manufacturers. They will have some feedback regarding valve and soft good limitations. There's also considerations to make sure your soft goods can handle propane and propylene service. Propane shouldn't be too problematic but propylene I BELIEVE becomes an issue with materials such as Buna-N or Nitrile. Would simply recommend looking into the service compatibility issues with the soft goods.

Thanks,
Ehzin

 

[Lebpower]

Thanks for your response Ehzin.

Looking at the existing Propane Propylene piping system at plant I notice that the valves installed are type "Ball", is there any reason for this?

Is not allowed to installed gate valves on this service?

 

[Ehzin]

My background is limited compared to most on this website and ball valves are actually scarcely encountered where I'm at. The only area I encounter them with any frequently is on some pipeline skids. Depending on the type of ball valve, resilient vs. metal seat you could run into temperature issues. Typically soft goods offer some significant limitations depending on how low temperature your process can get. I don't know exactly why gate valves would not be preferred. If you have them at low temperature it would be recommended or expected to either have extended bonnet or bellows seals. Extended bonnet attempts to remove the low temperature effects from your packing area by developing a vapor column, it also requires that the majority of the bonnet is not insulated and that the valve stem is in the vertical position or at least 45° from horizontal. Bellows seals simply have a welded in bellows to I suppose hermetically seal in the process, at least to prevent leaking thru the bonnet. Bellows can experience failures such as fatigue which could leak to leakage but how often that is would require some research.

So, questions. What type of ball valve are they? Some people would consider an Orbit a ball valve although it is fairly unique. And what are some of the materials used such as O-rings, seats if any, and gaskets? Are they resilient or metal seated?

Thanks,
Ehzin

 

[georgeverghese]

And dont forger that you still have to ask the pipe mill / valve suppliers for charpy impact testing at -50degC with A333.

 

[Ehzin]

Unless I'm mistaken A333 Gr. 6 should have impact testing as a requirement in spec versus a supplementary section or some after the fact testing. For the valve, it will depend on the material. Regardless, I would agree it is beneficial to specifically state it as a requirement.

Thanks,
Ehzin

 

[1gibson]

You'd get impact test results, but maybe not at the temperature you need them. -45*C is common, so that won't work if you need -50*C.

 

[Lebpower]

UPDATE

I specified ASTM A-333 considering the design temperature (-50ºC). However I was consulting to use A-106 Gr. B due to unavailability of A333, I made the consult to the Metallurgy department and they mentioned what 1gibson already mentioned above, the impact test are made at -45ºC.

So I necessary must use A333. Unless there's another way to evaluate the minimum temperature when I can use A106 with a specific thickness.

I was reading ASME B31.3 para. 323.3 Impact Test Methods and Acceptance criteriaand I found some curves that involve Thickness and Temperature, but I dont know how to use them.
I just thought that could be another way to determine if I can use ASTM A106 besides Impact test.


Thanks everybody for your help.

Blessings,

Roberto

 

[GD2]

A106 Gr. B can be used below -20F at the design temp of -50C subject to meeting some code rules. But before that we need to understand two temperatures - design temp and MDMT. I am not sure if the DEP SHELL Piping class specifies both the temps. Knowing MDMT is very important for exposing metal to low temp condition.
A106 Gr. B material can be used to a low temp of -20C. Code B31.3 allows to use A106 Gr. B material at a temp below -20c and give temperature reduction. It is based on the Stress Ratio. How to calculate the stress ratio is defined in notes under Fig. 323.2.2B. While calculating by notes 1 and 2 is easy, it needs a stress designer/engineer to calculate the ration by note 3. The rule is very simple. In simple words, if the line pressure is lowered than the design pressure, the piping can be used at a lower temp. The limit to use this rule is up to -48C.

As because your temp is -50C, the code will require the base metal, weld metal and HAZ impact tested. Low temp filler wire/ electrodes are used to qualify weld metal/HAZ. Sometimes, piping classes don't recognize the small margin of -48C and -50C and set the MDMT at -50C. Impact testing at -50C will be required per Table 323.3.1. Minimum impact value requirements are given in Table 323.3.5

 

[georgeverghese]

There is no way you will be permitted to use A106 Gr. B for a lower design temp of -50degC in a Shell piping class compliant design.

 

[Lebpower]

Thank you so much.

 

[GD2]

Lebpower,
As your design conditions itself are -50C/545psi, you are better off going for impact testing at -50C for base metal, weld metal and HAZ if you are using A106 Gr B. Weld metal and HAZ shall be qualified by a WPS then applying it to weld the piping. Follow the piping class to select all other piping materials.