FASTENER GUIDE

Many of our bolt styles are available in various grade and class options with each grade containing distinctive head markings. The following markings are the primary indicators used on our parts.

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Standard Parts

Grade of Material	Marking	Appearance	Nominal Size Range	Proof Load (PSI)	Yield Strength (Min. PSI)	Tensile Strength (Min. PSI)
Grade 2	No Marking		1/4" - 3/4" 3/4" - 1 1/2"	55,000 33,000	57,000 36,000	74,000 60,000
Grade 5	3 Radial Lines		1/4" - 1" 1" - 1 1/2"	85,000 74,000	92,000 81,000	120,000 105,000
Grade 8	6 Radial Lines		1/4" - 1 1/2"	120,000	130,000	150,000
18-8 & 316 Stainless	No Standard Marking		Up to 1"		45,000 minimum	85,000 minimum
A325 Structural Bolts	A325		1/2" - 1" 1 1/8" - 1 1/2"	85,000 74,000	92,000 81,000	120,000 105,000

Metric Parts

Class of Material	Marking	Appearance	Nominal Size Range	Proof Load (MPA*/PSI)	Yield Strength (MPA*/PSI)	Tensile Strength (MPA*/PSI)
Class 8.8	8.8		<16mm 16mm - 72mm	580 / 84,100 600 / 87,000	640 / 92,800 660 / 95,700	800 / 116,000 830 / 120,000
Class 10.9	10.9		5mm - 100mm	830 / 120,350	940 / 136,300	1040 / 150,800

*MPA = Megapascal. 1 MPA = 145 PSI (pounds per square inch)

Proof Load - The amount of tensile (pull apart) stress that a bolt must be able to withstand without permanent deformation.

Yield Strength - The amount of tensile stress at which a specific permanent deformation will take place.

Tensile Strength - The maximum amount of tensile stress that can take place before a bolt breaks or fractures.

Fastener SuperStore carries these grade options in the following standard categories:

Fastener SuperStore carries these grade options in the following metric categories:

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