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Class 300# piping

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DiegoMartinez

DiegoMartinez

Petroleum
Jul 1, 2006
65
Gents,

Could a expert person please verify the following?

The maximum operating pressure VS minimum temperature (0C) of carbon steel piping A106 Gr.B of class 300# is 51 Barg. I believe this is the maximum operating pressure of the 300# flanged vlave in a closed position in order to not stuff it. Pipes, fittings and flanged joints can sustain far more pressure than that. If the in line valves remains open, the pressure of the 300# can rise more than allowable pressure for class 300#.

Thanks
 
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Sorry if my response is not what you want to hear but Class 300 is limited near 46 bar in actual operation.

ASTM A 106 is the piping material. ASME B16.5 pertains to the flange material.

ASTM A 105 is a carbon steel flange listed in material group 1.1. This group permits among the highest pressure ratings for the flange class. Table 2-1.1 includes the Pressure-Temperature ratings for group 1.1 materials.

The maximum working pressure at zero degree C for Class 300 A 105 flange would be 51.1 Bar.

This is the maximum working pressure for the flange - not a valve or the pipe. Others can comment regarding the A 106 piping and fittings. The hydrostatic testing is performed at 1.5 times the design pressure. However, the pressure relief valves for a Class 300 system using material group 1.1 should not be set higher than 51.1 bar. In practice, you should not operate at more than 46 bar or 90% of the PSV set pressure without expecting a conventional PSV to begin leaking.
 
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Required hydrotest pressure should be specified as per the respective design code, which is not always 1.5

Allowable A106B pipe pressure will depend on the wall thickness chosen and its operating temperature range. That, of course, could easily be more or LESS than the ANSI#300 flange rating.



Going the Big Inch! [worm]
 
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I am not talking about the pressure test. It's just about the pressure a class 300# piping can sustain. I think it is more about the valve than a flange!
 
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Class 300 is not a piping class but a flange class. The material table mentioned is on page 23 of ASME B16.5-2003, Pipe Flanges and Flanged Fittings NPS 1/2 Through NP@ 24. Nothing in the flange class 300 nomenclature uses the term #. The piping class 300 applies to the flange class 300 from ASME B16.5; or B16.47 if applicable.

If the flanges are a material other than ASTM A 105 then the maximum pressure is different. Group 1.1 includes A 215 Grade WCB. Material group 1.2 is a bit higher for A 216 WCB and A 350 grade LF6 Class 2 - 51.7 bar at zero degree C. However, A 350 is limited to 42 bar, A 182 Grade F316L is rated 41.4 bar and B 160 is rated 33.1 bar.
 
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MEbrahim,

ANSI (and now ASME) 300# refers to flanges.

Typically, in a "ANSI 300#" system, all components must meet the minimum pressure requirements. And, usually, the weak links are the flanges.

So, a 300# valve will have 300# flanges (the weakest link), and be able to take 51 bar(approx) of pressure at -20 to 100 °F.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
 
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Ashereng,

Please, I think its better if you don't use the term "the weak link" when referring to anything in general. Its irrelevant that flanges could be a weak link, because many times they are not. The weak link could just as easily be any other component. The only important idea, and indeed the only requirement, is that both the pipe and the flange pressure ratings (and all subcomponent's) ratings are at least equal to the maximum allowed operating pressure of the system being designed.

Going the Big Inch! [worm]
 
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MEbrahim,

Out of curiosity, what kind of valves are you talking about specifically and at what operating temperature?

My comments....

Technically, for most valves, ASME B16.34, Valves - Flanged, Threaded, and Welding End, is the authority for the pressure temperature limitations and NOT ASME B16.5, Pipe Flanges and Flanged Fittings. Generally in the past, B16.5 and B16.34 were issued parallel to each other and the P/T ratings matched. Recently though, B16.5 revised its ratings and the corresponding B16.34 update wasn't released for couple years after. If you're playing close to the edge, be careful.

It's NOT OK to operate above the pressure rating at temperature whether the valves are open or closed. You're limited to the rating of the weakest link in your system whether it is the pipe, flange, valve, or other component. Short-term pressure excursions above the rated pressure are allowed as defined in the Piping Code that has jurisdiction over your system.

Note that some leakage is permissible across a closed valve per API 598, Valve Inspection and Testing. If you need something more strict, it needs to be specified with the valve purchase. Also resilient seated valves and valve containing elastomer parts or packing would have temperature ratings limited by those components.

Find additional information in the following:
API 600, Bolted Bonnet Steel Gate Valves for Petroleum and Natural gas Industries
API 602, Steel Gate, Globe and Check Valves for Sizes DN 100 and Smaller for the Petroleum and Natural Gas Industries

I hope this helps.


NozzleTwister
Houston, Texas
 
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BigInch,

Fair enough.

In my post, I did mention usually, when referring to the flanges.

Of course, this is not always the case.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
 
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One correction from a previous post is that material group 1.2 applies to A 216 WCC not WCB.

B16.5 still applies to flanged valves. The updates are not simultaneous and some differences exist. ASME B16.34 uses similar material groups with two tables, A-Standard Class and B-Special Class. Special Class valves include somewhat higher values but exclude flanges. My copy is B16.34-2004, Valves - Flanged, Threaded and Welding End. I have not checked to see the material group differences. I may do that another day.

For A - Standard Class Valves, group 1.1 includes A 216 Grade WCB for 51.1 bar. Material group 1.2 is 51.7 bar at zero degree C.

API 600 applies to gate valves, common in refinery service. My offshore experience includes mostly API 6D and API 608 ball valves. These also comply with ASME B16.34 and B16.5.

At the end of the day, Class 300 valves are limited near 51 bar at zero degree C. All are gauge pressure.
 
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I don't fully agree with what has been said here, particularly the way the question(s) have been answered.

The maximum operating pressure for the ANSI Class 300 system is 720 psig for operational temperatures -20/100 F. You can consult API 6D, Table 2.1 for other pressure levels verses thermal application. Note the listing is regardless of material considerations. Materials are typically governed by separate codes according to the application, CSA Z245.15 for valves in Canada, API for various oilfield equipment, etc. Piping have a considerable number of codes that can be accessed.

Some other answers discuss a 1.5 rating. One and one-half times the maximum operating pressure, 720 psig for ANSI Class 300 applications, is the maximum test pressure that the manufacturer of pressure containment equipment is obligated to "qualify" his design. This is typically hydrostatically charted for a period of time in front of third party inspectors designated as customer agents. In Canada, MTP hydrostatic pressure tests are mandatory under the valve code and those levels must be held for 30 minutes minimum.

When you are referring to open verse closed valves, the code does not recognize it as such. Rather, you may be interested with a shell test, opposed to a seat test which is conducted at 1.1 MOP for fifteen (15) minutes. In a closed valve configuration, you may be looking at the Inside-Out test for double block and bleed style valves, trunion mounted with independent seat activation.

I hope this clears the air somewhat and clarifies things.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
 
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Sorry, back to the flanges in B16.5 and to API SPEC 6D.

Between -20 and 100 degree F, the maximum pressure in psig is 740 for ASME Class 300 in material group 1.1 and 750 psig for material group 1.2. Material group 2.2 applies to A 182 Grade 316 forgings, A 351 Grade CF3M and CF8M where 720 psig is the maximum to 100 degree F. At 1000 degrees F the maximum pressure for Class 300 in material group 2.2 is 365 psig. Stainless is not rated as high at 100 degree F but higher than carbon steel at 1000 degree F where material groups 1.1 and 1.2 are only rated 85 psig for Class 300.

The ANSI logo appears obsolete for ASME standards. The forward suggests that the 2003 version will omit customary US or English units. The 2003 version has the ANSI blessing that is not shown on the title. Perhaps ASME will reflect the IEC in the future.

API Specification 6D, Twenty-second Edition January 2002, ISO 1413: 1999, MOD Petroleum and Natural Gas Industries - Pipeline Transportation Systems - Pipeline Valves

No table 2.1 exits.
 
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Gents,

Appreciate your postings. I wish I would have expand my question a bit more.

The material group is 1.1 and flange is of A105 material B16.5. The piping flanges used in this design are class 300 and the pipe is of sch 160. Ball valves used in the system are nothing out of ordinary and are API 6D. Unfortunately I have no standard to refer to at this stage.

The pressure of the above mentioned system is varibale from 49 to 56 Barg. Could you please tell me what is the permissible operation pressure of this syatem in the two following cases:

1- Class 300 valve is open
2- Class 300 valve is closed

Believe they must not be the same.

Many thanks
 
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System Design Specification

Piping Design Specification: =?
Temperatures: Min: = 0ºC, Max: = ?

Flange: ANSI#300 A105 = 740 psig = 51.02 Barg

Pipe: Diameter: = ?
Wall thickness: SCH 160
Pressure Calculation = Not Possible

Valve ANSI#300 API 6D: 740 psig = 51.02 Barg

The valve being Open or Closed does not affect the
Maximum Allowed Operating Pressure (MAOP)of
anything, although it will probably have some
influence on the maximum pressure IN the system.

So far, MAOP appears to be limited to 51.02 Barg, but please fill in missing information.

Going the Big Inch! [worm]
 
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Big Inch,

Info below as per your request:

Piping Design Specification: = ASME B31.3
Temperatures: Min: = -2ºC, Max: = 100

Flange: ANSI#300 A105 = 740 psig = 51.02 Barg

Pipe: Diameter: = 2"
Wall thickness: SCH 160
Pressure Calculation = Not Possible

Valve ANSI#300 API 6D: 740 psig = 51.02 Barg


 
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Biginch,

Liked your brief valuable reply. I was after a short reply like this!

Many thanks
 
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Your Class 300 Flanges are limited to 46.6 bar at 100 deg. C.

NozzleTwister
Houston, Texas
 
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