Valve material based on pipe material 4

[shameer786]

Hi Engineers... I am very new to this industry .. I Humbly request you to advise on valve material selection based on pipe material , I am Factory sales engineer so I always get trouble on this regard.... If you can advise me any article about this will be highly appreciable..

Thanks in Advance
Shameer

 

[gerhardl]

Your question is too general to give more than a general answer.

Roughly you can divide in two groups:

A. Common standard use for water, wastewater, non-corrosive fluids and more simple processes. The pipelines can vary in materials from GRP, plastics, iron, steels, protected, unprotected, stainless etc. The valves can and will vary in material not depending on material, and not depending on material on flanges or loose flanges, but selected on compability with fluid and according to necessary pressure class and certification.

This group will have 'normal practice' protection for possible galvanic corrosion between pipelines and valves (earthing, anodes or isolation).

B. Critical processes (example underwater, offshore processes, critical processes elsewhere). In such projects there will be special demands on material, material certification, construction, tests and certification, including demands on material compability to prevent galvanic corrosion both on pipelines and valves, in addition to normal certification and special certification to comply with the process pressure and temperature.

A lot of applications will fall in between those descriptions, but will very often have a 'normal practice' of what is acceptable.

Example: If you have a stainless steel pipeline in a certain pressure class and ask for valves suitable for the given fluid and pressure class, you will often get the cheapest valve material offered, which could be epoxy coated nodular iron, or primed only common steel, as this could be adequate and with a long lifetime for the given application.

If you explicit want offered 'all stainless steel valves' for the pipeline(at 3-10 times the price) you have to state this. In such cases you should specify for different options of valve materials to be able to select, at least at planning/evaluation project stage.

 

[JLSeagull]

Preferably use the piping specification to make the valve selection. This way a piping engineer has already done the real work regarding the fluid properties as well as the design pressure and temperature and the flange class. An easy exaple may be carbon steel. The piping may be specified as seamless ASTM A 106 grade B. The steel flanges are ASTM A 105. Perhaps a cast valve is A 216 WCB or WCC.

So how does the piping engineer make these selections?

 

[shameer786]

thanks Mr.JLSeagull and Mr.gerhardl ...

so your advise is that pipe meterial side piping engineers head ache?..... we people nothing do with this ?.....

 

[gerhardl]

Pipe- material and pipe general layout are normally selected before valves in a project, as piping is (normally)the largest cost and determining for the total plant/project layout.

Answer to you latest....

This does'nt mean that the valve engineer is pre-determined not to have an opinion, or that final lay-out and dimension is independent of valve selection. On the contrary, layout and dimension for regulating valves and check-valves and possibly others could require redoing of pipe-layout to obtain laminar flow and lower dimension than original pipeline, adaptions for access and operation etc.

The same is valid for selection of material and material combinations for each or special valves, or pipeline material before and after that special valve, demounting pieces etc.

....... and if everything else fail you could try to talk to eachother.... ;-) !

 

[JLSeagull]

I have nothing to do with assigning the piping specification to the process lines. The metalurgical work may be done by a process licensor. Some groups assemble the process flow and publish a material flow diagram differentiating sour or corrosive services from less troublesome areas. These flow diagrams establish the basic material selections. This may progress toward the piping specifications for that project.

Many of these line specification issues are dictated by corporate or industry standards. The line specifications may include a numbered index such as PIP PNCM0002 Piping Material Specifications Line Class Index. These apply specific metalurgies to various fluids broken down by flange class. The piping engineer then prepares specifications that identify details for each line code. Often these mention the requirements for radiographic examinations and other QA requirements. In my opinion the elastomers are the weak link in such specifications.

 

[reverman]

Below are some common pipe-cast-forge material equivalents for picking valve materials. As always be sure to check Pressure temperature tables to pick the right valve class

Pipe - Cast valve - Forged Valve

A106 GrB - A216 WCB - A105
P11 - A217 WC6 - A182 F11
P22 - A217 WC9 - A182 F22
P5 - A217 C5 - A182 F5
P9 - A217 C12 - A182 F9
P91 - A217 C12A - A182 F91
316 - A351 CF8M - A182 F316
316L - A351 CF3M - A182 F316L

 

[donf]

Selecting valve material based on pipe material doesn't always work.

A common example is 304 SS piping systems. While 304 pipe and fittings are readily available and less expensive than 316, the cast equivalent for 304 SS valves (CF8) is considered special, and is less available and more expensive than 316 SS valves (CF8M) - so - provided the application is compatible, it is quite common to specify 316 SS valves in a 304 SS system. PLEASE NOTE - 316 SS is not always an "upgrade" to 304 SS. Although rare, there are applications for which 316 SS is not suitable, but 304 SS is.

This is but one example. There are many others - so be sure to involve someone knowlegable in the field.

Regards,

donf

 

[shameer786]

Thank you for your valued comments..
I wish to say special thanks to Mr.reverman who provided me the answer which i really expect . B-)

Thanks
Shameer

 

[Tivari]

Hello Everyone,
I have a basic query related to the thread. Can P91 pipe be directly welded with a valve body made of SA217WC9?
Will be Grateful for quick help
Thanks
T

 

[Giuliano81]

Hi Tivari,
i don't think there will be any problems about it.

Regards
Giuliano

 

[davefitz]

Tivari:

re: P91 pipe to valving==> This is a common problem on modern powerplants- typically piping components using P91 have a design temperature of about 1050 F, well into the creep range. Problems we have seen in welding P91 piping to lower alloy valves is associated with the ASME loophole that allows the weld thickness to be based on the thinner components' required wall thickness, as opposed to the more conservative approach of requiring the weld thickness to be baed on the weaker alloy's required wall thickness.

We have seen prompt creep-fatigue failures ( within 1.5 yrs) of this weld interface when welding P91 to lower alloy valves and not having provided a F91 "transition piece", where the transition piece wall thickness at the valve would be based on the valve's lower allowable stress. So, for cases where the valve alloy is much weaker than the piping AND the weld is in the creep regime AND high thermal fatigue effects are expected , then do not use the ASME loophole and instead take the conservative approach and use a F91 transition piece.

 

[Tivari]

Giuliano, Thank you for the response.

However, As so clearly delineated by DaveFitz, the issue of weld thickness is very much there.

Thanks a lot, Davefitz, for reassuring the available options before us, as it is clear now that the F91 forging pieces, matching with the inferior and thicker valve at one end and the superior and thinner pipe at the other end HAS to be provided. Incidentally, this has been the practice at out firm so far(we do not take benefit of the ASME leeway), though I had attributed this requirement of matching piece solely to weld metal compatibility.

Which leads to the question that is SA217C12A is a perfectly stable material, fit for 40years service life etc?

Thanks
Tivari

 

[hsbcn]

Hi Shameer:

I second reverman's post. Here's a more complete list of pipe-cast-forge material equivalents of a wide variety of steels: carbon steels, low-temperature steels, standard stainless steels, and chrome-Moly alloys.

Hope this is helpful!

Heather Smith
Alloy valves from The Alloy Valve Stockist

http://duplex-valves.com

 

[ryanhu]

Hi reverman

good,Is that have more contrast about pipe, forge ,cast

such as A350 LF2...

completely,yes,completely will so good