Ningbo Datian Fastener Co., Ltd.
Ningbo Datian Fastener Co., Ltd.

The standard refers to the American ASTM or ASME standard with new and unique technical clauses added, which is suitable for a type of petrochemical fasteners used in high temperature and high-pressure environments, including bolts, studs, nuts, etc.

Petrochemical Fasteners

The mechanical properties and materials specified in GB/T3098/8 "Mechanical Properties of Carbon Steel Fasteners Part VIII Heat-resistant Threaded Connections" are suitable for fasteners that can withstand high temperature, alternating loads, and to a greater extent. Be sure to tighten the axial force.

High temperature and high-pressure petrochemical fasteners - commodity fasteners and special fasteners

1. Common Commodity Petrochemical Fasteners:

●The type and size of hexagon head bolts meet the requirements of GB/T5782, A and B grades. The mechanical properties of these petrochemical fasteners refer to the performance grades of carbon steel bolts according to GB/T3098/1 standard: A2-50, A4-50, A2-70, A4-70;

●The nut type conforms to GB/T6170 I-type nut and special nut (pipe flange nut). Its mechanical properties refer to the performance grades of carbon steel according to the GB/T3098/2 standard: grades 6 and 8; the performance grades of stainless steel nuts of GB/T3098/15 are A2-50, A4-50, A2-70, A4-70 ;

2. Special Petrochemical Fasteners:

●In order to be suitable for the conditions of high-temperature resistance, low-temperature resistance, and environmental corrosion resistance, formulate suitable special fasteners, such as full-threaded studs for pipe flanges, in accordance with the provisions of GB/T901. The dimensions of hexagon head bolts and nuts shall be carried out according to national standards.

●Selected materials (grades) include medium carbon alloy steels: 35CrMo (applicable temperature +100-525℃); 25Cr2MoV (applicable temperature>-20--575℃); 42 CrMo (applicable temperature +100-525℃). The strength is between 690~890Mpa, that is to say, the medium carbon alloy steel is tempered at high temperature (550℃<=tempering temperature<=600℃) to obtain comprehensive mechanical properties to meet the service of high-temperature environment.

●Stainless steel materials selected are: 0Cr18Mi9 (applicable temperature -196--800 ℃); 0Cr17Mi12Mo2 (applicable temperature +196--800 ℃); the strength of stainless steel material obtained by solution treatment is between 690~890Mpa, and the performance level is A2- 70 A4-50 A4-80 grade.

●Using American standards, using stainless steel grades and materials: ASTM A193 B8 CL.2 (for temperature +196-525℃); A193 B8M CL.2 (for temperature +196-525℃); A453660 (for temperature +29- 525℃); also includes A320L7 suitable for low temperature and high-pressure environment (applicable temperature -100℃).

●Special grade nut material (grade) can choose medium carbon alloy steel: 30CrMo, 35CrMo; guaranteed load