VMA Presentation Pressure Seal (MSS-SP-144) and ASME B16-2013 Update

Carlos E. Davila, PE

March 2014

CRANE FLUID HANDLING

Fugitive Emissions

Update

EPA has been reducing the allowable fugitive emissions on

valves in the last few years.

Due to the upcoming emission legislation, most refineries,

chemical and process industry plants will have to monitor their

emissions more closely

New industry standards are being published or revised for type

testing of valves to improve emissions in new valves

Better valves and sealing element designs will be replaced

during shut downs

Many aspects will be addressed to insure tight and minimal

emissions to comply with new legislation

2

History

Valve pressure seal design was last included as Appendix A in

the API 600 Standard, 10th Edition, February, 1997

API 600 Appendix A covered gate valves both Style A and Style

B, however, the industry used it for other valve types

It addressed the design using both API 600 as well as ASME

B16.34 wall thicknesses.

The appendix was not included in the API 600/ISO 10434 co-

branded document published as the 11th Edition of API 600

API did not want to include the design in the 12th edition

published in 2009 as API 600 and not co-branded with ISO

3

Pressure Seal Valve Design

History (Cont.)

Requests for a published document continued and it was

decided to approach ASME B16 for the possibility of including it

in B16.34.

Discussions within ASME B16 were held but decision was

reached that it would not be added to their documents.

The Manufacturers Standardization Society, MSS, was then

approached for consideration in preparing a standard

MSS agreed and it was placed in the TC 114, Steel Valves,

agenda for development

It was published as SP-144 with an edition date of 2013

4

Pressure Seal Valve Design

Bolted Bonnet

5

Leak

Path Leak

Path

Bolted Design

Bonnet uses external nuts and bolts to compress the bonnet

gasket.

High pressure / temperature conditions can force the bonnet

gasket seal apart, causing external leakage and fugitive

emissions

Typical Bolted bonnet design

Gasket Typically not to be used

Above Class 600

Pressure Seal

Pressure Seal Design

Valves use the process pressures to compress the bonnet

gasket

This eliminates leak paths to the atmosphere preventing

fugitive emissions

6 Typical Pressure Seal design

Gasket

Pressure

Pressure Seal

Design depends on pressure to creates a tight seal

The draw bolts will need to be adjusted due to compression of

gasket due to higher pressure.

7

Bonnet

Body Segment

Ring

Draw Bolt

Collar Draw Bolt

Collar

Bonnet

Body Segment

Ring

Typical Pressure Seal design

No Pressure Under Pressure

Gasket Gasket

Ret Ring Ret Ring

Typical Pressure Seal Nomenclature

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Pressure Seal

Developed by MSS and published in 2013

Covers original requirements of appendix A in the 10th

edition of API 600, 1997

Standard covers construction requirements for steel and

steel alloy valves

Applies to Gate, Globe and check valves

May be used in conjunction with other valve specific

standards

Includes parent standards in the Standard Practice

9

MSS SP-144

Parent standards include,

API 594, Check Valves; Flanged, Lug, Wafer, and Butt-welding

API 600, Steel Gate Valves- Flanged and Butt-welding Ends,

Bolted Bonnets

API 603, Corrosion-resistant, Bolted Bonnet Gate Valves –

Flanged and Butt-welding Ends

API 623, Steel Globe Valves – Flanged and Butt-welding Ends,

Bolted Bonnets

ASME B16.34, Valves-Flanged, Threaded, and Welded End

Not intended to replace requirements of the parent valve

standard except for modifications for pressure seal.

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MSS SP-144

Sizes and Pressure Classes

NPS 2 (DN 50) through NPS 50 (DN 1250)

Classes 600, 900, 1500, 2500 and 4500

For parent valve standard, API 600

Covers two styles of pressure seal bonnet valves

Style A valves in accordance with API 600, except modified with

ASME B16.34 minimum wall thicknesses and smaller diameter

seats and stems.

Style B valves in accordance with API 600.

11

MSS SP-144

For parent valve standard API 594

API 594 covers wafer single and dual plate valves as well as

swing check valves

Wafer valve can be provided without leak path to the

atmosphere

Swing check valves have bolted covers that can be modified to

the pressure seal design

Valve must meet wall thickness requirements

Stems are not effected

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MSS SP-144

For parent valve standard API 603

Valve must comply with all of the requirements of this parent

standard

No style A or B is covered

For Parent valve standard API 623

Recently published by API

Specifies stem diameters larger/different than API 600

Valve must comply with all of the requirements of this parent

standard

No style A or B is covered

13

MSS SP-144

Materials

Body and bonnet shall be an ASME B16.34 Group 1, Group 2, or

Group 3 material.

Gasket material shall be the manufacturer’s standard, but limited

to ductile iron, soft steel, austenitic stainless steel, vermiculite or

flexible graphite.

Pressure seal bonnet retention/sealing combination shall be the

manufacturer’s standard based on a tested and proven design.

Wetted metal part shall have a corrosion resistance at least

equivalent to the valve body material.

Adjustment bolting material shall be selected, or be coated, to

provide continuous serviceability during the valve’s service life.

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MSS SP-144

Design

For API 600 Style A gate valves

Body and bonnet wall thickness shall conform to the

requirements of ASME B16.34.

Inside diameter of seat openings shall not be less than 90%

of appendix A in B16.34 for valve NPS and pressure class.

If wedge gate is used, a flexible wedge shall be furnished

unless otherwise specified.

Minimum stem diameters shall be per Table 1.

15

MSS SP-144

Design (Cont.)

For API 600 Style B gate valves, double disc gate is not

permitted, unless otherwise specified.

API 600 gate valves require body and gate guide surfaces to

minimize wear and ensure alignment during full travel in all

orientations.

Only ASME B16.34 Standard Pressure Class valves are

covered.

Body-to-bonnet joint design requires that seal force increase as

internal pressure increases.

Requires bolting adjustment mechanism to pre-compress gasket

to allow standard production test to proceed

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MSS SP-144

Design (Cont.)

Designs utilizing segmental rings in body recess, Fig. 1, must

meet bearing, shear and bending stress requirements, such as,

For bearing stress at “a” location, Fig.1, body/segmental retaining

ring contact,

Pc x Ag/Aab ≤ K1S ≤ 10,500

Covers rules for retainers to secure bonnet/gasket sealing

structures

• For bolted flange retainers, the cross section must meet

ASME B16.34

• For threaded retainers, thread shearing area must meet

ASME B16.34

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MSS SP-144

Provisions in the valve design are required to allow the removal

of the segmental retaining ring

Marking

Shall be per MSS SP-25 and the parent standard.

For gates to API 600, marking shall include Style A or B as

applicable

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MSS SP-144

Typical dimensional nomenclature

Fig.1-Typical segmental retaining ring pressure seal joint

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MSS SP-144

Stems Style A

Table 1: Minimum stem diameters for API 600 Gate valves style A

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Stems Style B

21

Minimum stem diameters for API 600 Gate valves style B

ASME B16.34

2013 Edition

Approved by the ASME B16 Committee and published on

February 19, 2013.

3 year cycle to align with B16.5 and B16.47

Increase the size range from NPS 24 to NPS 50

Added reference to ASME B16.47 for flanges due to size range

increase

Some materials changed groups or were deleted

• Casting ASTM A351 Gr. CF3 moved from group 2.3 to 2.1

• Casting ASTM A351 Gr. CF3M moved from group 2.3 to 2.2

• Casting ASTM A351 Gr. CF8C deleted from group 2.5

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Proposed changes for the 2016 Edition

Pressure ceiling values

ASME B16 Case that offers an alternative ceiling pressure

for B16.34 Group #3, Nickel Alloy materials.

Can be applied to pressure-temperature ratings without

violating the "deflection rule"

Review material group alignment

Review present groups for 316 and 316L materials

B16 Case for ASME B16.34 valves from Unlisted Materials.

Expanding to Cover Valves up to NPS 60“ to match ASME

B16.47

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ASME B16.34

Questions?

Thank You