Compared to Hex Nuts, the Heavy Hex series is wider by 1/8" across flats. This provides a number of advantages. Heavy Hex Nuts can span eccentric or oversize bolt holes. They offer increased bearing area to support higher bearing stresses;and they have thicker walls to control nut dilation under load. These effects are most pronounced in the smaller sizes. RB&W stocks four grades of Heavy Nuts to meet various customer specification requirements. All are made in coarse thread only.
ASTM A307 grade for general applications is available in sizes from 1/4-inch through 4 inches.
ASTM A194 Grade 2 and 2H provide medium carbon steel product for high pressure and high temperature applications. Available in sizes 5/8 through 1-inch in coarse thread series. In sizes larger than 1-inch, both grades are stocked in 8-pitch series. Sizes 1-1/8 and 1-1/4-inch are also stocked in 7-pitch series for use with A325 and A490 bolts in tructural applications. Identification: a 2 or 2H on the top face.
A325 Grade for use with High Strength Bolts to ASTM
A325 specification. Identification: three circumferential dashes on the nut faces.


Made with dimensions identical to Hex Full Nuts. Six radial slots on the top permit proper alignment with a drilled hole in the end of a bolt to accommodate a cotter pin or safety wire for position locking. Sizes 1/4 to 1-1/2 inches, in both fine and coarse threads.


These nuts are made by blanking from low carbon strip or sheet steel. They are normally available double chamfered and double countersunk to permit assembly from either side. Such nuts are used on small, light assemblies where substantial strength and clamping force are rarely involved. Available in various finishes, such as zinc or cadmium plate; or with phosphate coatings. Stocked in sizes No. 5 through 3/8 inch.


Dimensions across flats are the same as those for Hex Nuts. Height dimension is approximately one-third larger than the Hex Thick Nut. High Nuts may be hardened and utilized for severe applications such as tractor pad bolts and spring shackle bolts. Stocked in sizes 3/8 to 1-1/4 inches, in fine thread only.


Dimensions across flats are the same as those for Hex Nuts, but they’re thicker in the height dimension. Purpose of this design is to provide additional thread engagement for severe fastening applications—such as those that require Grade 8 bolts. They are also produced slotted for use with cotter pins. Hex Thick Nuts are stocked in sizes 1/4 to 1-1/2 inches, fine thread only. Hex Thick Slotted Nuts are stocked in sizes 1/4 to 1-inch, fine thread only.


Similar to the Hex Slotted series, but wider by 1/8-inch across flats. Six slots milled into top of nut permit position locking with cotter pin or wire through drilled hole in bolt. Stocked in sizes 1/4 to 2 inches, in coarse thread only.


Like the slotted nut design, castle nuts have six radial slots to permit use of cotter pins or safety wire for locking into position. The chief difference is in the top of the nut. The castle nut permits the cotter pin or wire to be wrapped around its crown. Stocked in sizes 1/4 to 1-1/2 inches, in fine thread only.

SQUARE NUTs—This shape of nut is declining in use, being replaced by the more convenient, easierto- wrench, hex shaped product in almost all applications. Square nuts are sometimes specified for square head bolts. They have a chamfered top and flat face. The long dimension across corners enables them to span oversize bolt holes, and to withstand severe wrenching stresses. Stocked in sizes 1/4 to 1 inch. Available in coarse thread only.
HEAVY SQUARE NUTS—This series of nuts provides additional width and height where desirable, as in the case of bolts being used for non-critical assembly of steelwork. Heavy Square Nuts have a flat face and a chamfered flat or washer crowned top. Stocked in sizes 1/4 to 1 inch, in coarse thread only.

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