Thread protector is a fairly simple part, although it is subjected to very high requirements.
According to statistics, up to 10% of pipes supplied to the pipe depots of oil companies get damage of thread during the transportation due to poor quality and inadequate design of safety parts — thread protectors.
The protector should protect the threaded part of the pipe and the coupling from damage caused by hits during the transportation and handling, corrosion and contamination during the storage. Thus, it should perform its functions in the temperature range from -46 to +66°C.
Most of the current requirements for thread protectors, which the world’s largest pipe manufacturers are guided by, are currently regulated in the 9th edition of American Petroleum Institute API Spc 5CTs/international standard ISO 11960.
This standard defines three product specification levels (PSL) — PSL-1, PSL-2, PSL-3, which also apply to thread protectors. Every next level includes the requirements set out in the previous one, i.e. PSL-2 includes the requirements of PSL-1 and PSL-3 automatically includes the requirements of PSL-1 and PSL-2.

Requirements to thread protectors according to PSL levels are given in the following table:


Requirement PSL-1 PSL-2 PSL-3
1 Protector should not damage the pipe thread + + +
2 Protector should cover the full length of the thread + + +
3 Protector should prevent ingress of dirt and moisture to the threaded surface + + +
4 Protector should perform its functions within 1 year + + +
5 Protector material should not contain and components causing corrosion or adhesion to threads + + +
6 Protector material should perform its functions over the temperature range: -46C to +66C + + +
7 All-steel protectors are prohibited for use with 9Cr and 13Cr L80 tubular products + + +
8 Upon the agreement between the Supplier and the Consumer, the supplied open protectors may allow to perform a fixture test + + +
9 The protector’s manufacturer should register the protector design criteria, protector’s assembly and disassembly procedures, test results. This information should be available for both protector buyers and pipe consumers upon request. + + +
10 Protector should adjoin the end of a pipe or coupling tightly, without gaps/ + + +
11 Direct metal-to-metal contact is not allowed in the thread profile area or sealing surfaces. + + +
12 Protector material should withstand the destructive effects of UV radiation within 1 year. + + +
13 Protector should not be subjected to solvents (diesel fuel, acetone, varsol, trichlorethylene), thread lubricants and rust-preventing greases. + + +
14 For protectors providing the option of lifting by hook — the possibility of contact of hook and pipe’s and/or coupling’s end should be excluded. + + +
15 Protector should not change its the dimensions by more than a half of the thread profile height, in the temperature range from -46 to +66 degrees. + + +
16 Torsional moment of the protector should lie within the limits specified by the manufacturer in the temperature range from -46 to +66 degrees. + + +
17 Protector should not turn off by vibration (test according to MIL-STD-810). + + +
18 Protector should withstand the axial impact test in the temperature range from -46 to +66 degrees. Impact energy and axial impact test method are set in Annex I of the standard. + + +
19 Protector should withstand the 45 degree shock test in the temperature range from -46 to +66 degrees. Impact energy and axial impact test method are set in Annex I of the standard. + + +
20 Protector should prevent the thread’s corrosion within one year and withstand the salt spray chamber test in accordance with ASTM B117. + + +
21 Protector should pass the pipe break test + + +
22 Protector providing the option of lifting by hook should pass the test of lifting the pipe with protectors installed using the hook. + + +


Testing laboratory

To ensure product quality control and testing, our company has a testing laboratory.
The laboratory is provided with the equipment required for testing of thread protectors in accordance with API Spec 5CT/ISO 11960. These tests include:

  • Dimensional stability tests at temperature ranging from -46 to +66 °C.
  • Torsional moment tests at temperature ranging from -46 to +66 °C.
  • Vibration tests
  • Axial impact test at temperature ranging from -46 to +66 °C .
  • Impact test at angle of 45 o and at temperature ranging from -46 to +66°C.
  • Testing of anti-corrosion functions
  • Protector-stripping test
  • Test for checking the probability of hooking
Protector’s torsional moment test
Impact test bench
Stand for test tread to stall
Shake table

The equipment is certified by the Federal Agency for Technical Regulation and Metrology
The testing laboratory is open for cooperate and offers threaded protector testing services for manufacturers of pipes, thread protectors, and other parties concerned.

You can send a letter to the head of the testing laboratory:

+7 (473) 263-91-95 (ext. 1600)



The quality of our products is ensured by the following factors:

  • superior design and production technology
  • arrangement of production and quality control systems
  • application of original materials and compounds based on them

Quality management system of “CenterPlast” company complies with requirements of ISO 9001:2000 and has been certified by TUV-Turingen.

Our certificates: