Washers FAQs

Standards for Stainless Steel Flat Washers

What dimensional standards do stainless steel flat washers meet?

Stainless flat washers fall under the same ASME dimensional standards as your typical plain steel flat washer, which is ASME B18.21.1. Under ASME B18.21.1, dimensional tolerances for plain washers, there are two types specified, type A and type B. Type A has two series sizes to consider which include narrow and wide, while Type B... Read more

Lock Washers with A325

Can I use a lock washer in an A325 structural connection?

Looking through both the ASTM specification F3125 Grade A325 and the Research Council on Structural Connections (RCSC) website, we have found neither mentioning the use of lock washers in a structural steel connection.  We interpret this as neither allowing nor forbidding the use and that it would ultimately be up to the engineer of record... Read more

Bridge Washers

What is a bridge washer?

This is a term that is frequently used across the industry. More often than not, “bridge washers” will refer to cast iron malleable iron washers. These washers are typically used in dock and wood construction. Malleable iron washers are specifically designed to prevent bolt heads and nuts from pulling into the wood. Detailers will also... Read more

F844 Plate Washers

Do Portland Bolt’s round plate washers meet the requirements of ASTM F844?

If a purchaser specifies an ASTM F844 washer with the dimensions of Portland Bolt’s plate washers, then the washers do meet the requirements of F844. According to ASTM F844, a specification for general use steel washers, the washer dimensions must conform to ASME B18.21.1, Type A, Tables 1A and Tables 1B, unless otherwise specified. The... Read more

Domestic Washers

Are domestic flat washers a standard stock item?

Standard flat washers are a mass-produced item that Portland Bolt stocks as an accessory to accompany custom sized bolts we manufacture. A washer is a steel ring placed under a nut and/or bolt head to spread the pressure when the assembly is tightened. A washer also creates a smooth bearing surface for the nut to turn... Read more

Washers for Timber Bolts

Are timber bolts installed with a washer under the head of the bolt?

Timber bolts, also referred to as economy bolts in the Pacific Northwest, are designed with a round oversized head which eliminates the need for a washer underneath the head. The underside of the head has two nubs which bite into wood and prevent the head from spinning in the timber. The nubs under the head... Read more

Square F436 Washers

Does Portland Bolt make square F436 hardened washers?

Yes. There is a common misconception that ASTM F436 hardened washers are only available in the standard circular sizes. However, the F436 specification covers four defined styles of hardened washers, while also allowing for custom dimension washers as well. The four defined styles are: Circular Beveled Clipped Extra Thick These four styles each have specific tables... Read more

Extra Washers

Are there restrictions on using extra washers to accomodate tightening a nut onto a bolt that may be a bit too long and the nut is running out of thread?

Per the RCSC section 16.2-12, multiple washers are permitted under the nut in order to resolve this problem.

Stacking Washers with A325 Bolts

Is stacking of F436 washers acceptable with an A325 bolted connection?

Yes, in some cases the stacking of F436 washers seems to be allowed, but not in all cases. The Research Council on Structural Connections (RCSC) in Specification for Structural Joints Using High-Strength Bolts, December 31, 2009, page 16.2-12 says, “If necessary, the next increment of bolt length can be specified with ASTM F436 washers in... Read more

Welding Beveled Washers

Can I weld to your malleable beveled washers?

Along with shear plates and round malleable washers, malleable beveled washers are made with ASTM A47 cast malleable iron. See the following excerpts from ASTM A47. 11.3 Castings that have been repaired by the welding shall be reannealed so that the microstructure will comply with Section 8. (Section 8 of ASTM A47 lays out specific... Read more