ANSI / ASME B16.5 Flange Bolting

1.Boltings

Bolting listed in below table is recommended for use in flanged joints covered by this standard. Bolting of othe rmaterial may be used if permitted by the applicable code or government regulation. Bolting materials are subject to the limitations given in following paras.

1.1 High Strength Bolting

Bolting materials having allowable stresses not less than those for ASTM A193 Grade B7 are listed as high strength in below table. These and other materials of comparable strength may be used in any flanged joints.

1.2 Intermediate Strength Bolting

Bolting materials listed as intermediate strength in below table, and other bolting of comparable strength, may be used in any flanged joint provided the user verified their ability to seat the selected gasket and maintain a sealed joint under expected operating condition.

1.3 Low Strength Bolting

Bolting material having no more than 206MPa (30 ksi) specified minimum yield strength are listed as low strength in below table. These materials and others of comparable strength are to be used only in Class 150 and 300 flanged joints and only with gaskets. Flanged assemblies using low strength carbon steel bolts should not be used above 200°C (400°F) or below -29°C (-20°F).

1.4 Bolting to Grat Cast Iron Flanges

The following recommendations are made in recognition of th elow ductility of gray cast iron.

  • Alignment of flange faces is essential along with control of assembly bolt torque so as not to over-stress the cast iron flanges. Care must also be excercised to ensure that piping loads transmitted to cast iron flanges are controled, taking into account its lack of ductility and recognizing that cast iron flanges should not be used where suddenly applied loads such as rapid pressure fluctuations may occur.
  • Where Class 150 steel flanges are bolted to Class 125 cast iron flanges, the gaskets should b emade of Annex C, Group No. 1a materiasl, steel flanges should have flat faces, and (1) low strength bolting with the limitations of the para 1.3 should be used with ring gasket extending to the bolt holes, or (2) bolting of low (para 1.3), intermediate (para 1.2), or high (para 1.1) strength may be used with full face gaskets extending to th eoutside diameters of the flanges.
  • Where Class 300 steel flanges are bolted to Class 250 cast iron flanges, the gaskets should be made of Annex C, Group No . 1a materials, and (1) low strength bolting with the limitations of para 1.3 should be used with the gaskets extending to the bolt holes and with the flanges having either raised or flat faces, or (2) bolting of low (para 1.3), intermediate (para 1.2), or high (para 1.3) strength may be used with full face gaskets extending to the outside diameters of the flanges and with both the Class 300 steel and Class 250 cast iron flanges having flat faces.

2. Flange Bolting Dimensions

2.1 Dimensional Standards

Stud Bolts, threaded at both ends or threaded full length, or bolts may be used in flange joints. Dimensional recommendations for bolts, stud bolts and nuts are shown in below table. Also see table 2 for bolting material recommendations.

2.2 Bolt Lengths

Stud bolt lengths, including the heigh tof two heavy hexagon nuts, are shown as dimension L in all dimension tables. The tablulated stud bolt length L does not include the height of the end points. An end point is defined as an unthreaded length, such as a chamfer, which extends beyond the thread. The method of calculating bolt lengths is explaine din Annex D. The tabulated bolt lengths are reference dimensions. Users may select other bolting lengths.

2.3 Bolting Recommendations

For flange joints, stud bolts with nut at each end are recommended for all applications as especially for high temperature services.

Table 1
Table 1C Flange Bolting Dimensional Recommedations
Product Carbon Steel Alloy Steel
Stud Bolts ASME B18.2.1 ASME B18.2.1
Bolts smaller than 3/4 in. ASME B18.2.1, square or heavy hex head ASME B18.2.1, heavy hex head
Bolts equal to or larger than 3/4 in. ASME B18.2.1, square or heavy hex head ASME B18.2.1, heavy hex head
Nuts Smaller than 3/4 in. ASME B18.2.2, heavy hex ASME B18.2.2, heavy hex
Nuts equal to or larger than 3/4 in. ASME B18.2.2, hex or heavy hex ASME B18.2.2, heavy hex
External Threads ASME B1.1, CL 2A course series ASME B1.1, CL 2A course series up through 1 in;
eight thread series for larger bolts.
Internal Threads ASME B1.1, CL 2B course series ASME B1.1, CL 2B course series up through 1 in;
eight thread series for larger bolts.
Table 2
Table 1B List of Bolting Specifications
Applicable ASTM Specifications
Bolting Material (Note 1)
High Strength (Note 2) Intermediate Strength (Note 3) Low Strength (Note 4) Nickel and Special Alloy (Note 5)
Spec. No. Grade Notes Spec. No. Grade Notes Spec. No. Grade Notes Spec. No. Grade Notes
A193 B7 ... A193 B5 ... A193 B8 Cl.1 (6) B164 ... (7)(8)(9)
A193 B16 ... A193 B6 ... A193 B8C Cl.1 (6)
  A193 B6X ... A193 B8M Cl.1 (6) B166 ... (7)(8)(9)
A320 L7 (10) A193 B7M ... A193 B8T Cl.1 (6)
A320 L7A (10)
A320 L7B (10) A193 B8 Cl.2 (11) A193 B8A (6) B335 N10665 (7)
  N10675 (7)
  A193 B8 Cl.2B (11)
A320 L7C (10) A193 B8C Cl.2 (11) A193 B8CA ...
A320 L43 (10) A193 B8M Cl.2 (11) A193 B8MA ... B408 ... (7)(8)(9)
  A193 B8M Cl.2B (11)
  A193 B8T Cl.2 (11) A193 B8TA (6)
A354 BC ... B473 ... (7)
A354 BD ... A320 B8 Cl.2 (11) A307 B (12)
  A320 B8C Cl.2 (11) B574 ... (7)
A540 B21 ... A320 B8F Cl.2 (11) A320 B8 Cl.1 (6)
A540 B22 ... A320 B8M Cl.2 (11) A320 B8C Cl.1 (6)
A540 B23 ... A320 B8T Cl.2 (11) A320 B8T Cl.1 (6)
A540 B24 ... A320 B8T Cl.1 (6)
  A449 (13)
  A453 651 (14)
  A453 660 (14)
Genaral Notes :
  • Bolting material shall not be used beyond temperature limits specified in the govering code.
  • ASME Boiler and Pressure Vessel Code, Section 2 materials may also be used provided the requirements of the ASME specifications are identical or more stringent than the corresponding ASTM specifications for the Grade, Class or Type listed.

NOTES :
  • Repair welding of bolting material is prohibited.
  • These bolting materials may be used with all listed materials and gaskets.
  • These bolting materials may be used with all listed materials and gaskets, provided it has been verified that a sealed joint can be maintained under rated working pressure and temperature.
  • These bolting materials may be used with all listed materials but are limited to Class 150 and Class 300 joints. See para 5.3.4 for recommended gasket practices.
  • These materials may be used as bolting with comparable nickel and special alloys parts.
  • This austenitic stainless material has been carbide solution treated but not strain hardened. Use A194 nuts of corresponding materials.
  • Nuts may be machined from the same material or may be of a compatible grade ASTM A194
  • Maximum operating temperature is arbitrarily set at 260°C (500°F) unless the material has been annealed solution annealed, or hot finished because hard temper adversely affects design stress in the creep rupture range.
  • Forging quality is not permitted unless the producer last heating or working these parts tests them as required for other permitted conditions in the same specifications and certifies their final tensile, yeild and elongation properties to equal or exceed the requirements for one of the other permitted conditions.
  • This ferritic material is intended for low temperature service. Use A194 Gr. 4 or Gr. 7 Nuts.
  • This austenitic stainless material has been carbide solution treated and strain hardened. Use A194 nuts of corresponding material.
  • This carbon steel fastener shall not be used above 200°C (400°F) or below -29°C(-20°F). See also Note (4). Bolts with drilled or undersized heads shall not be used.
  • Acceptable nuts for use with quenched and tempered bolts are A194 Gr. 2 or Gr. 2H Mechanical property requirements for studs shall be the same as those for bolts.
  • This special alloy is intended for high temperature service with austenitic stainless steel.

3. Bolt Cross-sectional Area

B1.2 Bolt Cross-sectional Area
Total flange bolting cross-sectional area requirements are based on the following relationship

Ab ≥ {PcAg/7000}

where
Ab = total effective bolt tensile stress area
Ag = an area whose circumference is defined by a diameter equal to the raised face dimension R in Table 4
Pc = pressure rating class designation or number (e.g., for class 150, Pc = 150, for Class 300, Pc = 300)