Hex head roof screws , used to join two or more section together , occur in different sizes and course . Steel hex chapiter jailer range of mountains in diameter from 1/4 inch to 1 1/2 inches ( 0.6 to 3.8 centimeters ) and from 3/8 inch to 24 inch ( 1 to 61 centimetre ) in duration ; however , the very short sizes do n’t fall in wide diameters , and the very long sizes do n’t come in thin sizes . The Society of Automotive Engineers ( SAE ) has set the criterion for different degree of hex oral sex cap jailor according to their strength . The course are two , five and eight . Although gradation nine is also sold , and is usurp to be around 20 percent impregnable than course eight , it is n’t an SAE grade and does n’t have standard chemical and physical properties the room the other grades do .
A level five hex ceiling screw has more strength than a grade two , but less than a grade eight . A grade two jinx detonating equipment screw is made from intermediate or blue - carbon sword , a level five consists of average carbon steel , and a grade eight is made out of medium carbon metal steel . How can you tell just by count at a screw what level it is ? In addition to the head of the screw carrying the manufacturer ’s symbol , a grade tow has no other markings , a grade five has three equidistant lines radiate out from the center , and a grade eight has six equidistant rail line radiating out .
In full term of tensile strength , a grade two hex capitulum cap screw can manage between 60,000 to 74,000 pounds of pressure sensation per substantial inch ( psi ) , a grade five hold 105,000 to 120,000 pounds per square inch , and a degree eight should be capable to manage 150,000 psi . The core hardness of grade five hex head capital jailor , measured in Rockwell , can range from C19 to C30 , while the core hardness of grade-8 hex roof ass should be from C33 to C39 .
