§192.145 Valves. Which design standards apply to control valves?

Control valves in pipeline systems could have several different functions.  They could be used to control pressure and flow, or as isolation valves to shut down a pipeline.

The question arose concerning control valves.  When designed and installed to control flow and pressure and not act as an isolation valve, must they still meet the IBR requirements of API 6D.

PHMSA provides the answer in the following interpretation.

Interpretation 192.145  24

September 3, 2014

 

 

U.S. Department of Transportation

Pipeline and Hazardous Materials Safety Administration

1200 New Jersey Ave, S.E.

Washington, D.C. 20590

 

Mr. Lee Strobel

Senior Mechanical Engineer

Flow & Process Technologies

GE Oil & Gas

1550 Greenleaf Avenue

Elk Grove Village, IL 60007

 

Dear Mr. Strobel:

In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated November 18, 2013, you requested an interpretation regarding the federal gas pipeline safety regulations in 49 CFR Part 192. Specifically, you asked whether the § 192.145 design standards for pipeline valves apply to control valves. You stated that you are referring to the type of control valves that would be used on large transmission pipelines or city gate stations typically having a size range of 6 inches or higher and can operate at pressures exceeding 1,000 pounds per square inch as opposed to small valves serving individual buildings.

You noted that each valve must meet the minimum requirements of API 6D (incorporated by reference, see § 192. 7), or to a national or international standard that provides an equivalent performance level, but your view is that API 6D seems to specifically relate to on-off isolation valves and has no specific provisions for control valves. You stated that it is generally accepted in the valve industry that most control valves do not meet the seat leak tightness requirements of API 6D, instead they must meet the seat leak tightness requirements of IEC-60534-4 or ANSI/FCI 70-2-2013, which are less stringent than API 6D. In addition, you commented that there does not seem to be a definition of the term ‘valve’ in § 192.3, so it is unclear to you whether the § 192.145 requirement includes both on-off and control valves.

You also suggested that PHMSA may want to consider whether control valves should be classified as regulators because you believe they essentially perform the same function of regulating the flow.

Section 192.145 states in its entirety:

192.145 Valves.

(a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API 6D (incorporated by reference, see § 192.7), or to a national or international standard that provides an equivalent performance level. A valve may not be used under operating conditions that exceed the applicable pressuretemperature ratings contained in those requirements.

(b) Each cast iron and plastic valve must comply with the following:

(1) The valve must have a maximum service pressure rating for temperatures that equal or exceed the maximum service temperature.

(2) The valve must be tested as part of the manufacturing, as follows:

(i) With the valve in the fully open position, the shell must be tested with no leakage to a pressure at least 1.5 times the maximum service rating.

(ii) After the shell test, the seat must be tested to a pressure not less than 1.5 times the maximum service pressure rating. Except for swing check valves, test pressure during the seat test must be applied successively on each side of the closed valve with the opposite side open. No visible leakage is permitted.

(iii) After the last pressure test is completed, the valve must be operated through its full travel to demonstrate freedom from interference.

(c) Each valve must be able to meet the anticipated operating conditions.

(d) No valve having shell (body, bonnet, cover, and/or end flange) components made of ductile iron may be used at pressures exceeding 80 percent of the pressure ratings for comparable steel valves at their listed temperature.

However, a valve having shell components made of ductile iron may be used at pressures up to 80 percent of the pressure ratings for comparable steel valves at their listed temperature, if:

(1) The temperature-adjusted service pressure does not exceed 1,000 p.s.i. (7 Mpa) gage; and

(2) Welding is not used on any ductile iron component in the fabrication of the valve shells or their assembly.

(e) No valve having shell (body, bonnet, cover, and/or end flange) components made of cast iron, malleable iron, or ductile iron may be used in the gas pipe components of compressor stations.

Whether a valve used in a gas pipeline system is used to control the pressure and flow of the gas or to completely shut it off, the valve still affects the safety performances of a pipeline system. Section 192.145(c) states “Each valve must be able to meet the anticipated operating conditions” which requires the valve seat tightness or shut-off capabilities to meet operational conditions. Therefore, control valves must meet the minimum requirements of API 6D or to a national or international standard that provides an equivalent performance level in accordance with §192.145.

The seat type and tightness of a valve used to control flow volumes or pressures may be specified by the end-user based upon the type of operational conditions that exist to meet 49 CFR Part 192.  For example, a valve that controls maximum allowable operating pressure for overpressure protection (a type of control valve) would require a higher level of seat tightness than a valve used only for flow volume control.  In most operational situations, a control valve used for overpressure protection control would require a second control valve or relief valve for overpressure protection to get the desired level of seat tightness needed for overpressure control.

Your comment concerning grouping control valves and regulators for purposes of design standards requirements is beyond the scope of an interpretation because PHMSA responds to interpretation requests based on the current Federal pipeline safety regulations.

If we can be of further assistance, please contact Tewabe Asebe of my staff at 202-366-5523.

Sincereley,

 

John A.Gale

Director, Office of Standards and Rulemiking

 

*********************************

 

GE Oil & Gas

Mr. Lee Strobel

Senior Mechanical Engineer

Flow & Process Technologies

GE Oil & Gas

1550 Greenleaf Ave.

Elk Grove Village, IL 60007

Tel: (847) 6313713

Cell: (312) 662 0107

E-mail: lee.strobel@ge.com

 

Office of Pipeline Safety (PHP-30)

PHMSA, US Department of Transportation

1200 New Jersey Avenue SE

Washington, DC 20590-0001

18 November, 2013

 

Dear Sir/Madam,

I am writing to request a formal interpretation of a section of your 49 CFR 192 regulation, relating to transportation of natural and other gas by pipeline.

Section 192.145, giving requirements for valves, states that: ‘Except for cast iron and plastic valves, each valve must meet the minimum requirements of API 60 (incorporated by reference …). or to a national or international standard that provides an equivalent performance level.’ However, API 60 seems to specifically relate to on-off isolation valves and has no specific provisions for control valves.

For example, it is generally accepted in the Valve Industry that most control valves do not meet the seat leak tightness requirements of API 60 – instead they must meet the seat leak tightness requirements of IEC-60534-4 or ANSI/FCI 70-2-2013, whkh are less stringent than API 60. This seems understandable, as the main function of a control valve is to regulate the pressure and flow, rather than to shut off and seal for isolation purposes.

So, our key questions are:

  • Under 49 CFR 192, are control valves required to conform to API 60?
  • If not, then what standards are control valves expected to conform to?

There does not seem to be a definition of the term ‘valve’ in 192.3, so it is unclear whether this is intended to include both on-off and control valves. Another point to consider is that it could be argued that control valves should be classified along with ‘regulators’, as they essentially perform the same function of regulating the flow. If it is the case that control valves should be categorized as regulators, then what requirements are regulators expected to meet?

To clarify, I am referring to the type of control valves that would be used, for example, on large transmission pipelines or city gate stations, as opposed to more local distribution to individual buildings. Such valves tend to cover a size range of 6″ or higher and can operate at pressures exceeding 1000 psi.

We would be most grateful for any guidance you can provide.

Yours sincerely,

 

Lee Strobel

Dresser, Inc.

 All this and more in WinDOT on the Web, The Pipeline Safety Encyclopedia.

Make the regulations accessible to all your personnel.  Go to www.49cfrpipeline.com.

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