1、 MSS SP-141-2012 Multi-Turn and Check Valve Modifications Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE Vienna, Virginia 22180-4602 Phone: (703) 281-6613 Fax: (703) 281-6671 E-mail: infomss-hq.org MS
2、S www.mss-hq.org MSS STANDARD PRACTICE SP-141i This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 310 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide an effe
3、ctive, clear, and non-exclusive standard that will benefit the industry as a whole. This MSS Standard Practice describes minimal requirements and is intended as a basis for common practice by the manufacturer, the user, and the general public. The existence of an MSS Standard Practice does not in it
4、self preclude the manufacture, sale, or use of products not conforming to the Standard Practice. Mandatory conformance to this Standard Practice is established only by reference in other documents such as a code, specification, sales contract, or public law, as applicable. MSS has no power, nor does
5、 it undertake, to enforce or certify compliance with this document. Any certification or other statement of compliance with the requirements of this Standard Practice shall not be attributable to MSS and is solely the responsibility of the certifier or maker of the statement. “Unless indicated other
6、wise within this MSS Standard Practice, other standards documents referenced to herein are identified by the date of issue that was applicable to this Standard Practice at the date of approval of this MSS Standard Practice (see Annex A). This Standard Practice shall remain silent on the validity of
7、those other standards of prior or subsequent dates of issue even though applicable provisions may not have changed.” By publication of this Standard Practice, no position is taken with respect to the validity of any potential claim(s) or of any patent rights in connection therewith. MSS shall not be
8、 held responsible for identifying any patent rights. Users are expressly advised that determination of patent rights and the risk of infringement of such rights are entirely their responsibility. In this Standard Practice, all text, notes, annexes, tables, figures, and references are construed to be
9、 essential to the understanding of the message of the standard, and are considered normative unless indicated as “supplemental”. All appendices, if included, that appear in this document are construed as “supplemental”. Note that supplemental information does not include mandatory requirements. Non-
10、toleranced dimensions in this Standard Practice are nominal, and, unless otherwise specified, shall be considered “for reference only”. Excerpts of this Standard Practice may be quoted with permission. Credit lines should read Extracted from MSS SP-141-2012 with permission of the publisher, Manufact
11、urers Standardization Society of the Valve and Fittings Industry. Reproduction and/or electronic transmission or dissemination is prohibited under copyright convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fittings Industry Inc. All rights
12、 reserved. Originally Approved: May 2011 Originally Published: November 2011 (2012 Edition) MSS is a registered trademark of the Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright , 2011 by Manufacturers Standardization Society of the Valve and Fittings Industry
13、, Inc. Printed in U.S.A. MSS STANDARD PRACTICE SP-141ii TABLE OF CONTENTS SECTION PAGE 1 SCOPE . 1 2 TERMS AND DEFINITIONS 1 3 OVERALL MODIFICATION REQUIREMENTS . 1 4 MARKING, TRACEABILITY, ASSEMBLY, DISASSEMBLY, AND STORAGE 3 Specific Modification, Evaluation, and Testing Procedures 5 BORE AND END
14、CONNECTION CHANGES . 4 6 TRIM CHANGE 8 7 NACE MR0103 AND MR0175 COMPLIANCE . 10 8 PACKING AND GASKET REPLACEMENT . 10 9 MISCELLANEOUS MODIFICATIONS 11 10 TESTING AND NONDESTRUCTIVE EVALUATION . 13 ANNEX A Referenced Standards and Applicable Dates . 15 MSS STANDARD PRACTICE SP-1411 1. SCOPE 1.1 This
15、Standard Practice establishes minimum requirements for the modification of new gate, globe, and check valves, which have been manufactured in accordance with recognized national standards, and require modification to meet specific end-user requirements. 1.2 The purpose of this Standard Practice is t
16、o ensure that the quality of workmanship and materials meet all applicable standards and codes. 1.3 The procedures contained within this Standard Practice are general in nature and the facility performing the modification(s) may need to augment them as necessary to achieve compliance with all applic
17、able codes and standards. 2. TERMS AND DEFINITIONS 2.1 Bluing Also called “Prussian Blue”. An indelible ink paste designed to be applied to closely mating parts to confirm the closeness of their fit. 2.2 End-User The ultimate owner and/or user of a valve. 2.3 Low-Stress Stamp Alphanumeric or symboli
18、c steel stamps designed to reduce stress raisers in the components they are stamped upon. 2.4 Match Marks Scribed or written marks used to match the specific orientation of a valve during disassembly and reassembly. 2.5 OEM The original manufacturer of the valve. 2.6 Relevant Indication (PT Examinat
19、ion) As defined in ASME Boiler taking into consideration a 1/16” pull-back allowance on each nipple. 5.9.4 Cut nipples to required length. 5.9.5 Insert nipple and make slight scratch mark at port to nipple interface. Slide nipple out 1/16”, mark again, and tack weld to hold in place. 5.9.6 Weld nipp
20、le into valve in accordance with Section 3.5, utilizing a fillet type joint. 5.9.7 Welds shall be visually and dye penetrant inspected in accordance with ASME B31.3, Section 341, with acceptance criteria in accordance with Section 341.3.2, for normal fluid service. 5.9.8 Pressure test in accordance
21、with API 598. 6. TRIM CHANGE 6.1 Scope This procedure details the changing of valve trim on valves by the installation of new OEM supplied trim components, or by weld overlay of existing components, or the manufacture of new components by fabrication and/or machining. Trim materials include those li
22、sted in API 594, Table 3; API 600, Table 8; and API 602, Table 12; as well as additional materials specified by a written customer purchase order. 6.2 Valve is disassembled in accordance with Sections 4.1 and 4.2. 6.3 Seats 6.3.1 If available, new OEM replacement seats of the proper material are ins
23、talled in the valve by welding or threaded in, as applicable. 6.3.2 Seats may be overlaid with weld filler metal or machined from solid wrought or forged material. 6.3.3 Seats may be machined and welded in situ or removed from the valve for overlay and machining. 6.3.4 Composition of solid seat ring
24、s or weld overlay filler material shall meet the nominal trim chemistry as specified in API 594, API 600, API 602, API 603, or other applicable parent valve standard. 6.3.5 Solid seats shall be made to the same dimensions of the existing seat ring and threaded or welded into the valve. If welded in,
25、 weld in accordance with Section 3.5. MSS STANDARD PRACTICE SP-1419 6.3.6 Prior to weld overlay of the existing seats, the seating surface area of seat shall be machined back .100”. 6.3.7 Weld filler material of the proper chemistry is overlaid onto the seating surface area to a minimum depth of .12
26、5”. 6.3.8 The seat is machined to the dimensions of the original seat. Sharp edges shall be broken or chamfered to decrease the risk of disc damage during operation. 6.3.9 The seating area is examined via liquid penetrant. No relevant indications are allowed. 6.3.10 The seat is threaded or welded in
27、to the valve body. If threaded, a light lubricant may be used to prevent thread galling during assembly. 6.3.11 For API 602 valves, the seat is swaged-in, in accordance with the manufacturers specifications. 6.4 Disc 6.4.1 If available, a new OEM replacement disc of the proper material is installed
28、in the valve. 6.4.2 Original disc may be overlaid with weld filler metal or a new disc machined from solid wrought or forged material. 6.4.3 Chemical composition of new solid disc or weld overlay filler material shall meet the nominal trim chemistry as specified in API 594, API 600, or API 602, or a
29、s requested on the customer purchase order. 6.4.4 Prior to weld overlay of the original disc, the seating surface area of disc shall be machined back .100”. 6.4.5 Weld filler material of the proper chemistry is overlaid onto the seating surface area to a minimum depth of .125”. 6.4.6 The disc is mac
30、hined to the dimensions of the original disc. Sharp edges shall be broken or chamfered to decrease the risk of seat damage during operation. 6.4.7 The seating area is examined via liquid penetrant. No relevant indications are allowed. 6.5 Stem 6.5.1 If available, a new OEM replacement stem of the pr
31、oper material is installed in the valve. 6.5.2 For API 600, 602, and 603 valves, a new stem matching the dimensions of the original stem is machined from a single piece of wrought or forged bar stock. 6.5.3 Stem backseat and packing area shall have a surface roughness of 32 micro-inches or smoother.
32、 6.5.4 Out-of-straightness of the entire length of the stem shall not exceed 0.001” per inch. 6.5.5 A maximum taper or cylindrical variation of 0.002” across the entire stem packing area. 6.6 Backseat 6.6.1 Original backseat may be overlaid with weld filler material or machined from solid forged or
33、wrought stock of the correct chemistry. 6.6.2 Backseat surface finish shall be 32 micro inches or smoother. 6.6.3 Examine the seating area of the backseat via liquid penetrant, in accordance with MSS SP-93 or ASME B16.34, Appendix II. No relevant indications are allowed. 6.7 Fitting 6.7.1 Seats and
34、disc shall be lapped or polished and checked with bluing or feeler gauges to confirm correct angle and fit. 6.7.2 Backseat and stem backseat area shall be lapped or polished and checked with bluing or feeler gauges to confirm correct angle and fit. MSS STANDARD PRACTICE SP-14110 6.8 Valve is assembl
35、ed in accordance with Section 4.3 or 4.4. 7. NACE MR0103 AND MR0175 COMPLIANCE 7.1 Bolting 7.1.1 Most end-users consider body/bonnet bolting to be directly exposed to a sour environment in the event the gasket begins to leak and bolting strength is compromised due to corrosion of the bolting. 7.1.2
36、Use caution when substituting softer modified bolting, such as B7M for B7, as the strength of the resulting bolted joint may be compromised. 7.2 Overlays onto Martensitic (400-series) stainless steel require PWHT after welding to prevent hard areas in the heat-affected-zone (HAZ). 7.3 Some OEM auste
37、nitic stems, particularly on small API 602 valves, may have rolled threads, rendering the material too hard for use in sour service. Hardness should be verified, before installation or certification, to NACE MR0103. 7.4 When certifying valves for sour service hardness, readings should be taken on al
38、l accessible wetted components; especially seat ring seal welds and HAZ, overlay welds and HAZ, and backseat seal welds and HAZ. 8. PACKING AND GASKET REPLACEMENT 8.1 Resilient Gasket Replacement 8.1.1 Scope This procedure details replacement of the original gasket with a type specified in a written
39、 customer purchase order; including, but not limited to, graphite laminate and spiral-wound types. 8.1.2 Valve is disassembled in accordance with Section 4.1 and 4.2. 8.1.3 Gate valve discs should be left in the valve body to protect against damage, if possible. 8.1.4 Existing gasket is discarded. 8
40、.1.5 New gasket of proper dimensions, material, and design is installed. 8.1.6 Valve is assembled in accordance with Section 4.3. 8.1.7 Maximum operating temperature on the valve tag must be changed to the maximum operating temperature of the gasket, if lower than original valve maximum operating te
41、mperature. 8.1.8 Pressure test in accordance with API 598. 8.2 Pressure Seal Gasket Replacement 8.2.1 Valve is disassembled in accordance with Section 4.2. 8.2.2 New pressure seal gasket is installed in accordance with manufacturers instructions. 8.2.3 Valve is assembled in accordance with Section 4
42、.4. 8.2.4 Pressure test in accordance with API 598. 8.3 Braided Packing Replacement 8.3.1 Scope This procedure details the installation of braided rope style packing; including, but not limited to, graphite and Teflon materials. 8.3.2 Valve is disassembled in accordance with Section 4.2. 8.3.3 All p
43、acking residue shall be removed, taking care not to scratch the stuffing box interior and the stem (if disassembly is not required). Existing packing shall be removed using either compressed air or nitrogen to blow the packing out of the packing chamber, or by pulling the packing using packing pulle
44、rs or packing picks. Visual or tactile verification shall be performed to ensure that all existing packing remnants have been removed. MSS STANDARD PRACTICE SP-14111 If visual verification cannot be carried out, tactile verification shall be acceptable using either a probe or packing pick. The packi
45、ng chamber shall be cleaned of packing remnants using compressed air or nitrogen. 8.3.4 Confirm packing cross-section dimension by measuring area between stem and stuffing box I.D., and by measuring existing packing. 8.3.5 New packing rings are measured and cut at a 45oangle. 8.3.6 A minimum of five
46、 and a maximum of nine packing rings should be installed. A minimum 60% travel length must remain on the packing gland after hydro-test. Carbon bushings may be utilized below packing to adjust chamber depth, if necessary. 8.3.7 Install the packing set in the packing chamber (stuffing box), re-assemb
47、le the packing gland flange/gland assembly, and tighten the packing retaining nut(s) or bolting. Packing retaining nut(s) or bolting shall be adjusted, alternately, with no more than one quarter (1/4) turn at a time until the final torque is obtained. Final torque is per manufacturers specification,
48、 or if not available, per ASME PCC-1. 8.3.8 Packing gland adjustment length remaining after installation of packing material and after pressure testing shall be greater than 25% of the minimum packing depth. 8.3.9 Test valve in accordance with API 598. 8.3.10 Maximum operating temperature on valve t
49、ag must be changed to maximum operating temperature of packing, if lower than original maximum operating temperature. 9. MISCELLANEOUS MODIFICATIONS 9.1 Bypass Installation 9.1.1 Scope This procedure details the construction and attachment, by welding, of bypasses onto cast or forged steel valves. 9.1.2 If required, valves shall be disassembled in accordance with Sections 4.1 and 4.2. Valves not disassembled shall follow the guidelines of Section 4.1. 9.1.3 Bypass design shall be confirmed by written customer purchase order. If not supplied or specified by the customer, by
