Monolithic Insulating Joint One Piece Insulating Joint A694 F70

Product Introduction

The monolithic insulating joint is a general name for the joint which can substitute insulation flange and has both the sealing performance required by buried steel pipe and the electrical insulation performance required by electrical corrosion protection engineering. The utility model comprises a pair of internal and external connecting parts, and an insulating seal coat in the middle of the connecting part and a pair of steel short pipes welded with the connecting part respectively. It is an important component for cathodic protection of pipeline in pipeline transportation in order to prevent electrochemical corrosion. It has higher stiffness than insulation flange, can bear large bending moment, high insulation performance, long life, and can be buried in the installation.

The monolithic insulating joint is composed of the following parts： upper pipe, lower pipe, sleeve, insulating parts, sealing parts, insulating coating.  There are insulating parts and sealing parts in the upper and lower pipes of the insulation joint butt end parts, forming a double sealing structure with insulation performance. The sleeve adopts groove welding or direct welding with the upper conduit. The insulating parts and the upper and lower pipes are firmly sealed inside to form a "sealed container", which not only has a good insulating effect, but also greatly improves the bearing capacity of the insulating structure.

Materials

1.The metal material of the insulation joint shall be the killed steel smelted by electric furnace or oxygen converter, and the steel smelted at a temperature lower than -20°C shall be refined outside the furnace.

2.The technical requirements of steel should meet the design requirements of the relevant pipeline engineering design department.

3.The steel used for insulation joint manufacturing shall have quality certificate, and the manufacturer of insulation joint shall check and accept the steel according to the quality certificate.

4.Forgings used for compression elements shall comply with NB/T 47008 and NB/T 47009.

5.Forgings used for compression components should be selected according to the design pressure, weight and size.

Fields of application

This standard is applicable to the monolithic insulating joints with a nominal diameter of no more than 600mm and a design pressure of no more than 16MPa and a nominal diameter of no more than 1400mm and a design pressure of no more than 12MPa, referred to as insulating joints, in the electric corrosion protection engineering of steel pipelines of buried or above ground transportation of petroleum and natural gas. Its applicable design temperature range is -45℃ ~ 100℃.

Quality Requipments

Insulation strength：2500V 50Hz 1 minute no breakdown or arc;

Insulation resistance： DC 1000V resistance ≥6M ω;

Hydrostatic test pressure： 1.5 times of design pressure;

Airtight test pressure： equivalent to design pressure;

Non-destructive testing： according to JB4730-94, all butt joints are 100% radiographic inspection, and all other bearing welds are 100% magnetic particle inspection;

Groove： adopt API5L standard.

Installation Requipments

1. Avoid welding within 50 meters of the installation of insulation joints;

2. After connecting the insulation joint with the pipeline, do not lift the pipeline within 5 meters of the joint;

3. Pressure test of insulation joint and pipeline instrument.