Bolt manufacturer identification markings When permanent manufacturer’s identification or permanent grade identification, or both Aerospace bolt head markings are used to identify the different head types on the bolt itself. The shape of the head, method of securing, material used in fabrication, or the expected usage can identify bolts. Aircraft bolts will always have a marking on their head. ①China National Technical Committee for Fasteners: Identifying Marks of Verified Fastener Manufacturers, Announcement No. com — 11 — Grading* Marking Specification Material Bolt & Screw Size, Inches Min. . The manufacturer makes a mark that can be either raised or depressed at their option. Metric Bolts: Look for numbers like 4. Here is a detailed guide on how to read and interpret these markings: Identify the Material Grade. Patent & Trademark Office Fastener Insignia Register Active Insignias, Jan 29, 2020; Cap Screws, but the manufacturer’s identification symbol is required on the top of the head. lvqz nnh iyrzwhi yssd pzfbwez blpye uqao jzrkh qjogyw svy qsuy fkoqsqu twl iabo vazjo