2.4. INSULATING JOINT & INSULATING FLANGES

The purpose of insulating joints installation on gas and oil pipelines, it is to ensure electrical isolation among sections of pipelines preventing detrimental electrochemical interaction among the sections themselves. Insulating joints are also used to ensure effective current spreading on cathodic protection systems.

The insulating joint is suitable for installation either under, or above ground. It shall be installed on pipeline by means of girth welding it between two sections of pipeline itself.

It includes assembly, insulation board, packing, sealing ring, such as a short tube. It is the alternative to insulating flange.

Insulation extrusion welded joints using the form of a whole shall not be used bolt flange connection type. Joints will be insulated using insulation and sealing material into the folder and fixed in the sleeve (assembly) in a form. 

Insulation joints after assembly, to the internal components should be fixed in the appropriate location. Pressure in the soil to provide for a pipeline operating pressure and balance of plant or a water pressure test at the scene, the entire insulation joints intact. 

Insulation joints sealed internal components in joints close to the insulation board, a permanent flexibility, and sealing the two sides of components of direct contact with the exposed metal surface will not move to ensure the tightness of the joints.

• Good insulation: 2500V shake table testing insulation resistance ≥ 200MΩ, breakdown voltage ≥ 3KV. 
• Long life: life with the same pipeline, and strength. 
• High intensity: pressure test ≥ 1.5PN (design pressure). 
• Temperature: -30 ℃ - +90 ℃.
• Application media: oil, gas, water, chemical raw materials, such as coal slurry. 

The investigation of the materials you used to meet the following requirements:

• Insulating materials: high-strength epoxy resin and glass fibers in line with the Layered materials: ASTM D709 G11. 
• Flexural strength: longitudinal ≥ 390MPa, horizontal ≥ 290MPa; 
• Tensile strength: longitudinal ≥ 340MPa, horizontal ≥ 240MPa; 
• Compressive strength: ≥ 340MPa; 
• Water Absorption: ≤ 30mg; 
• After the water resistance of ≥ 5 * 108Ω 
• Breakdown voltage ≥ 35KV 
• Steel body combination: 16Mn, JB4726, ASTM A694 F52, F60 
• Short tube: 20 #, 16Mn, GB8163-99; X70, X65, X56, X52, X46, API SPEC.5L. 
• Sealing material: O-shaped or U-shaped seal ring: fluorine rubber, nitrile butadiene rubber-based, consistent with ASTM D2000. 
• Filling material: cold-solid resin; 
• Insulating coating; imports of liquid epoxy resin; 
• Anti-corrosion materials: heat-shrinkable anti-corrosion materials

Insulating flanges are those flanges equipped with plastic pieces that insulate and prevent the flow of an electric current between two metal surfaces. Insulating flanges are used in cathodic protection systems to prevent electrolytic corrosion.  It includes a pair of steel flanges, insulation between the two flange seals, fasteners and fastening flange insulation parts and two-phase welding flange has a pair of short steel tube. 

Insulation flange  is mainly used in gas transmission and distribution pipelines and gas regulator, metrology, storage and other devices.  The main role is to protect the gas distribution segment, equipment and pipeline insulation between isolation.  This protects them from chemical corrosion, extending the service life of pipelines and equipment.  Our products comply with SY/T0516-1997 "insulating flange design provides" standard.

The insulation product according to their different seals are divided into:

1. Pressure sealing flange-type insulation (the insulation flange-I); and
2. Self-seal flange-type insulation (the insulation flange type II) in two. 

1. With a buried pipeline, electrical corrosion protection works required by the performance of electrical insulation. 
2. Medium in the pipe required temperature, under pressure from the work of a long-term reliable and adequate strength and sealing performance. 
3. Reasonable structure, assembly, demolition, replacement parts easily. 

1. Applies to medium natural gas, city gas, liquefied petroleum gas, light oil. 
2. Medium temperature -10 ~ +60 ℃. 
3. Ambient temperature -20 ~ +60 ℃. 
4. Insulation resistance ≥ 500ΚΩ. 
5. Breakdown voltage of ≥ 3KV. 
6. Pressure range: PN0.6MPa, PN1.0MPa, PN1.6MPa, PN2.0MPa, PN2.5MPa PN4.0MPa, PN6.4MPa 
7. Product specifications: DN15 ~ 1400