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
8
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.
10
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
12
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.
14
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
16
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
17
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
18
MSS SP-144
Typical dimensional nomenclature
Fig.1-Typical segmental retaining ring pressure seal joint
19
MSS SP-144
Stems Style A
Table 1: Minimum stem diameters for API 600 Gate valves style A
20
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
22
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
23
ASME B16.34
Questions?
Thank You
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