Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts
Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts
(OP)
Hi all,
For duplex stainlees steel flanged joints, we had specified ASTM A453 Gr. 660 bolts and ASTM A194 Gr. 2HM nuts (as per API 6A). However, we propose to change the nuts to a corrosion-resistant alloy (CRA) material. Can someone let me know any CRA material grades for nuts that are compatible with Gr. 660 bolts ? The main concern here is galling. Can we use nuts to A453 Gr. 660 (same grade as bolts)?
Would appreciate if you could share your experiences/observations on CRA nuts on Gr. 660 bolts.
Thanks,
Balvendra Pal
For duplex stainlees steel flanged joints, we had specified ASTM A453 Gr. 660 bolts and ASTM A194 Gr. 2HM nuts (as per API 6A). However, we propose to change the nuts to a corrosion-resistant alloy (CRA) material. Can someone let me know any CRA material grades for nuts that are compatible with Gr. 660 bolts ? The main concern here is galling. Can we use nuts to A453 Gr. 660 (same grade as bolts)?
Would appreciate if you could share your experiences/observations on CRA nuts on Gr. 660 bolts.
Thanks,
Balvendra Pal





RE: Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts
ASTM A453 specification covers standards for Grade 660 (Class A, B, C, and D) , Grade 651 (Class A and B), Grade 662 (Class A and B), and Grade 665 (Class A and B) of bolting materials,with ten classes of yield strength ranging from 50 to 120 ksi [345 to 827 MPa], for use in high-temperature service such as fasteners, for pressure vessels and valve flanges. Bolting materials in ASTM A453 are covered rolled, forged, or hot-extruded bars, and also bolts, nuts, screws, washers, studs, and stud bolts. Grade 660 (A286, UNS S66286) has a PREN of 16.8. Grade 660 nuts used with 660 bolts will gall at a low threshold galling stress (see link).
http://www.nickelinstitute.org/~/Media/Files/Techn...
RE: Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts
RE: Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts
For example, can we use ASTM A194 Gr. 8MA (SS316) nuts with Gr. 660 bolts ? Is there data available for threshold galling stress for this material combination ? Service is non-sour, low temperature (up to 40 deg. C) and 300 lb. pressure rating.
RE: Nuts Material Grades Compatible with ASTM A453 Gr. 660 Bolts