STAINLESS STEEL BUMAX ALL METAL SELF LOCKING FLANGED NUTS

Bumax Flat Washers — A standard-series flat washer manufactured in Bumax's A4/316 stainless, used under a bolt head, nut, or screw to spread clamping load evenly across the joint face and protect the substrate from surface marking during tightening. Because it shares the same high-tensile fastener range, this washer is most often specified alongside Bumax nuts, bolts, and screws in marine, offshore, structural, and process-industry assemblies where both the corrosion resistance of 316-grade stainless and full mill traceability are needed for certified or safety-critical work — plain A2 stainless or zinc-plated washers are usually adequate where the assembly won't see a corrosive environment or doesn't require documented material provenance. Choosing between this standard-series washer and the Large Series Flat Washer in the same range comes down to bearing area: the standard washer suits typical clearance-hole assemblies, while the large series version's bigger outside diameter is worth specifying where the joint material is softer, the clearance hole is oversized, or the load needs spreading over a wider footprint. Sizing is straightforward — match the washer's bore diameter to the bolt, screw, or stud it's paired with, and use a thickness appropriate to the property class and preload involved, since a too-thin washer can deform under a high-tensile Bumax fastener's full clamping force. Flat washers are typically fitted under the nut, under the bolt head, or both, and become particularly important wherever oversized clearance holes are used or the joint surface would otherwise be damaged by direct contact with the fastener head or nut face. As with the rest of the Bumax range, every batch is traceable back to the original mill, supporting the certification requirements common on regulated marine, structural, and process-industry projects.

FAQs
Can Bumax Flat Washers be used with standard, non-Bumax bolts and nuts?
Yes — sizing follows standard metric bore diameters, so they're compatible with any correctly sized bolt or nut. Where full documented traceability matters for a project, however, every component in the assembly, not just the washer, needs to be sourced to the same standard.

What thickness should I choose for a high-preload joint?
Choose a thickness appropriate to the fastener's property class and expected preload; an undersized or overly thin washer can deform or flatten under a high-tensile Bumax bolt's full clamping force, reducing the reliability of the joint over time.

Does this washer need to match the property class of the Large Series version?
No — both are made from the same A4/316 stainless, so the choice between standard and large series is about bearing area and hole size rather than strength class.