Flowserve Mach 1 - Manual (Page 5)

5
User Instructions Mach 1 High Performance Plug Valve - DVENIM0300-01 - 03.13
®
SECTION IV
PRESSURE CONTAINING FASTENERS
MATERIAL SELECTION
Selecting the proper fastener material is the ultimate responsibility of
the customer because the supplier does not typically know in what
service the valves will be used or what elements may be present in
the environment. Flowserve normally supplies B7 (carbon steel) for
ductile cast iron and carbon steel valves. For stainless steel and high
alloy valves, B8, Class 2B (stainless steel) fasteners are supplied as
standard. All fasteners used must have a minimum yield strength of
65,000 PSI, a minimum elongation of 25% and be compatible with
the process fluid. Determining compatibility to the process fluid goes
beyond a material being resistant to general corrosion
because the more important consideration is a material’s resistance
to stress corrosion cracking. Depending on the service, it may make
sense to use B7 fasteners on high alloy valves. One such service
would be marine environments because of stainless steel’s suscep-
tibility to stress corrosion cracking in chloride environments.
Another key aspect of fasteners is frequent visual inspection.
Because of the common practice of using steel fasteners rather than
stainless steel to avoid chloride stress corrosion cracking, visual
inspection is recommended
to monitor the general corrosion of these fasteners. If jacketing or
insulation is used on a valve, it must be periodically removed
for visual inspection of the fasteners. If you wish assistance in
determining the proper fasteners to use, please refer to the
attached chart.
DESIGN & TyPE
Flowserve’s valve design standards adopt ASME B18.2.1 (1996,
Addenda 1999) as the standard for fastener type and design. This
national standards requires that finished hex ‘head’ cap screws
be used when the head of the fastener is turned. A finished hex
‘head’ cap screw and a heavy hex cap screw have a bearing
surface under the head to minimize frictional resistance during
tightening. They also comply to qualified body diameters and
fully formed head dimensions. Cookeville Valve Operation’s poli-
cy is to use finished hex ‘head’ and heavy hex ‘head’ cap screws
for all pressure retaining fasteners. This includes top caps, pack-
ing adjusters, plug adjusters, bottom caps, body halves or other
pressure retaining components. Compliance is made with
ANSI B18.2.2 (1987, reaffirmed 1993), Square and Hex Nuts,
when studs and heavy hex nuts are required. Additional informa-
tion on these items may be obtained from the Flowserve
Corporation, Cookeville Valve Operation, Cookeville,
Tennessee.
* These options should be limited to glass ISO valves.
** CL 600 valves are limited to these alloys.
HHCS - Finished Heavy Hex Head Cap Screw Alloy identification stamp required on each piece.
HCS - Finished Hex Head Cap Screw Certification required.
STUD - Stud Alloy Specification (40 KSI Minimum Yield Strength, 12% Minimum Elongation)
Dimensions per ASME B18.2.1
B9 - Stainless Steel per ASTM A193, Class 2B, Grade B8 (AISI type 304)
B16 - ** Stainless Steel per ASTM A193, 100% hardness tested
B7 - ** Chromium - Molybdenum Alloy Steel per ASTM A193, Grade B7
B7M - Chromium - Molybdenum Alloy Steel per ASTM A193, Grade B7M, 100% hardness tested
B7MT - Chromium - Molybdenum Alloy Steel per ASTM A193, Grade B7M, 100% hardness tested, PTFE coated, Dupont SP11C,
Type B - Color blue or green
B8M - 316 Stainless Steel per ASTM A193, Grade B8M, Class 1, 40 KSI Min. Yield Strength, 12% Min. El.
B8C2 - 304 Stainless Steel per ASTM A193, Grade B8, Class 2
C20 - * Carpenter C20, CB-3 (UNS NO8020), ASTM B473, 40 KSI Min. Yield Strength, 12% Min. El
HC - * Hastelloy C276 (UNS N10276), ASTM B574
I625 - * Inconel 625 (UNS N006625), ASTM B446
I825 - * Incoloy 825 (UNS N08825), ASTM B425, 40 KSI Min. Yield Strength, 12% Min. El.
IN - * Inconel 600 (UNS N0660), ASTM B166, 40 KSI Min. Yield Strength, 12% Min. El.
M - * Monel (UNS N04400), ASTM B164, Class A or B, 40 KSI Min. Yield Strength, 12% Min. El.
HB - Hastelloy B (UNS 10665), ASTM B335
I718 - ** Incoloy 718, AMS 5595B
MKH - * Monel K-500, Cold drawn and aged hardened, QQN-286 and ASTM F468
L7 - ** Chromium-Molybdenum Alloy Steel per ASTM A320, Grade L7
L7M - Chromium-Molybdenum Alloy Steel per ASTM A320, Grade L7M, 100% hardness tested
L7T - ** Chromium-Molybdenum Alloy Steel per ASTM A320, Grade L7, Teflon® coated, Dupont SP11C, Type B - Color blue or green
L7MT - Chromium-Molybdenum Alloy Steel per ASTM A320, Grade L7M, 100% hardness tested, Teflon® coated, Dupont SP11C, Type B - Color blue or green
N-200 - * Nickel per ASTM B160 (UNS N0220), 40 KSI Min. Yield Strength, 12% Min. El.
B7YC - ** Chromium-Molybdenum Alloy Steel per A193, Grade B7, Yellow Zinc Dichromate Plated
TABLE I
CAP SCREWS - STUDS