STUDS & NUTS
Studs & Nuts (As per 6A & ANSI B16.5)
1.1 Brief Description
PARVEEN manufactures and supplies studs, nuts to meet requirements of all API flanges as per API-6A, as well as flanges as per ANSI B-16.5 and MSS-SP-44 & BS 3293.
Studs & Nuts for API Flanges (Table - 1)
Studs Nuts shall meet the requirements of the applicable ASTM specs unless otherwise noted. Dimension and thread pitch shall be as per ASTM A -193 for studs and ASTM A 194 for nuts. The mechanical properties as specified in the table. API flanges takes precedence from those required by ASTM.
Yield strength shall meet or exceed the minimum shown in the table. Material size limitations specified in ASTM A-320 for Gr L7M may be exceeded if the material requirement are met.
NACE Class - I Studs
a. UNS No. 05500 in the hot rolled and age hardened condition will have a hardness of HRC 35 or lower and a minimum yield strength of 105000 PSI (725 MPA) for dia's upto 2.5" and of 95000 PSI for Larger sizes.
b. ASTM a 453 Gr 660 solution treated and age hardened will have a hardness of HRC 35 and lower and a Minimum yield strength of 105,000 PSI for dia's upto 2.5" and of 95000 PSI for larger sizes.
NACE Class. II Studs
a. ASTM a 193 Gr B7M is provided at a minimum yield strength of 80,000 PSI for the API flanges for NACE MR 01-75
Class II only.
b. ASTM a 320 Grade L7M is provided at a minimum yield strength of 80000 PSI for the API flanges for NACE MR 01-
75 Class II only.
NACE Class. III Studs
a. ASTM a 193 Gr B7 is provided for non exposed service for the API flanges for NACE MR 01-75 Class III only. b. ASTM a 320 Gr L7 is provided for non exposed service for the API flanges for NACE MR 01-75 Class III Only.
a. ASTM a 194 Gr. 2 HM is provided for all API flange sizes and rated working pressure.
b. For NACE Class I, UNS no. 05500 or ASTM A 453 Gr. 660 nuts can be used with NACE Class I bolting after making provisions to prevent galling.
Studs & Nuts for ANSI B - 16.5 Flanges (Table - 2)
Bolting materials for high strength bolting having allowable stress not less than those for ASTM a 193 Gr. B7 are also listed. These and other materials of comparable strength can be used. Bolting materials for intermediate strength at low strength are also listed in the Table 2. Minimum yield strength for low strength bolting is 30 KSI (207 MPA). Flanged joints using low strength carbon steel bolts will not be used above 4000 F (2000C) or below -200 F (-290C)