Heavy hex nuts are available in a number of grades and specifications including: ASTM, SAE, and AASHTO.
Round U-Bolts - Portland Bolt
Heavy Hex Nuts, ASTM A194/A194M and ASME SA194/SA194M, 2HM, Plain, PDF
A Comprehensive Thread Pitch Chart for Construction Fasteners Produced by Portland Bolt & Manufacturing Co. Since 1912, PDF, Tools
Peel Rivets™ - Aluminum/ Steel, PDF, Rivet
Result1/2: Cypnest 2020
Credit Application - Portland Bolt
Fastener Marking Requirements - Portland Bolt
A Comprehensive Thread Pitch Chart for Construction Fasteners Produced by Portland Bolt & Manufacturing Co. Since 1912, PDF, Tools
Result1/2: Cypnest 2020
PROCO Flexible Joints, PDF, Pipe (Fluid Conveyance)
ASTM A563 DH Heavy Hex Nuts - Galvanized Hex Nuts
Hardware ASTM A325
Hex vs. Heavy Hex Nuts - Portland Bolt