ASTM A182 Stainless Steel Anchor Flange

The ASTM A182 stainless steel anchor flange is an important supporting component in large-diameter, high-internal-pressure, long-distance gas (oil) pipeline systems. In places with lower pressure, it can be replaced by a short pipe with a thrust ring, or called a wall sleeve.

For the connection of fixed pipelines that are required to be buried underground or not to be repaired for life, and when the pressure required is relatively high, if the anchor flange uses a conventional flange, it cannot ensure the safe and reliable operation of the high-pressure pipeline.

The utility model is an axisymmetric annular body with a flange, and the two sides of the flange are symmetrical flange necks. The ports of the two flange necks are respectively welded to the ports of the pipeline and buried in the anchor pile.

Since the two flanges connected by bolts in the prior art are combined together, the anchor flange eliminates the sealing gasket and is made into an integral flange, which is connected to the pipeline by welding and fixed to the anchor pile by its flange and flange body, so that it can be used for the connection of fixed pipelines.

ASTM A182 Stainless Steel Anchor Flange Heat Treatment

The main function of heat treatment is to eliminate the stress of forgings, reduce the surface hardness of forgings, and improve the machining performance; adjust and improve the overheating and coarse structure formed during the forging process; reduce the inhomogeneity of the chemical composition and metallographic structure inside the forgings, further refine the grains, and improve the comprehensive performance of the product.

After the forging of the anchor flange is completed, the chemical composition is first sampled for re-inspection, and rough processing is carried out after passing the rough processing.

After rough processing, ultrasonic flaw detection and surface coloring detection are carried out, and tempering heat treatment is carried out after passing the qualification. The heat treatment adopts the quenching and tempering, and the equipment adopts a parallel furnace.

ASTM A182 stainless steel anchor flange requires fast heating, uniform furnace temperature, and a small temperature difference between the upper and lower working areas. It is equipped with a control instrument to monitor the temperature in the heat treatment furnace in real-time. When heating, the temperature difference of the 6 temperature measuring points should not exceed ±10℃.

When the anchor flange is loaded into the furnace, a uniform space is left between the forgings to make the forgings evenly heated to ensure the comprehensive mechanical properties of the workpiece.

ASTM A182 Stainless Steel Anchor Flange Quality Inspection And Performance Inspection

Anchor flanges must undergo multiple quality inspections after forging and heat treatment, including re-inspection of chemical composition, ultrasonic non-destructive testing, physical and chemical performance testing, pressure bending tests, etc., to ensure the high quality of the product.

In the production process of anchor flanges, under the witness of the supervisor, the manufacturer conducts a physical and chemical performance test on each batch of products according to the same smelting furnace and the same heat treatment furnace. At the same time, the first batch of products are sent to a third party for physical and chemical performance testing to ensure that the mechanical properties and chemical composition meet the technical requirements, thereby proving the compliance and stability of the process and providing quality assurance for the product. The finished product’s external dimensions, forging ultrasonic testing, surface coloring testing, and sleeve weld quality RT and UT testing are 100% inspected piece by piece.

In addition, to ensure the safe and reliable performance of the anchor flange, one piece of the first batch of anchor flanges DN1000mm that has passed the inspection is selected for a pressure bending test before manufacturing.

After the physical and chemical performance tests are qualified, the anchor flange shall be finished, including the finished appearance dimensions and welding grooves. The structural dimensions of the anchor flange are determined after verification by finite element stress analysis, and the anchor flange forgings are not allowed to be welded. Therefore, the appearance quality and dimensions of the forgings are checked piece by piece to ensure that there are no harmful defects such as cracks, interlayers, folds, and slag inclusions that are visible to the naked eye.

To ensure the welding quality of the anchor flange and the pipeline, the anchor flange is welded and anti-corrosion treated with sleeves at the manufacturer. A qualified welding process assessment is the basis of the welding process instruction book. Before welding the sleeve, the manufacturer conducted welding process assessments for forgings and sleeves to determine the weldability of forgings and pipeline steel and the mechanical properties after welding. After welding, the weld is subjected to stress relief heat treatment and 100% radiographic flaw detection.

The anti-corrosion of the anchor flange uses a double-layer polyethylene heat shrink sleeve for patching. The heat shrink sleeve is a three-layer structure consisting of a two-component liquid epoxy bottom layer and a radiation cross-linked polyethylene heat shrink patch sleeve.

The surface rust removal, preheating temperature, baking temperature of heat shrink sleeve, and method of rolling out bubbles of anchor flange all affect the quality of the anti-corrosion layer.

To meet the technical conditions proposed by the design, the supervisors and anti-corrosion technicians of the production plant have conducted many studies and tests before the anti-corrosion construction and explored a set of construction process parameters that have been proven to be suitable. The anchor flanges are treated with anti-corrosion strictly according to the qualified process parameters. At the same time, the adhesion of the anti-corrosion layer is regularly checked in proportion to verify the stability of the anti-corrosion process.

ASTM A182 Stainless Steel Anchor Flange Machining, Sleeve Welding, And Anti-Corrosion

After the physical and chemical performance tests are qualified, the anchor flange shall be finished, including the finished outer dimensions and welding grooves. The structural dimensions of the anchor flange are determined after verification by finite element stress analysis, and welding is not allowed for anchor flange forgings. Therefore, the appearance quality and dimensions of the forgings are checked piece by piece to ensure that there are no harmful defects such as cracks, interlayers, folds, and slag inclusions that are visible to the naked eye.

In order to ensure the welding quality of the anchor flange and the pipeline, the anchor flange is welded and anti-corrosion treated with sleeves in the production plant.

The anti-corrosion of the anchor flange adopts a double-layer polyethylene heat shrink sleeve for patching. The heat shrink sleeve is a three-layer structure consisting of a two-component liquid epoxy bottom layer and a radiation cross-linked polyethylene heat shrink patch sleeve. The surface rust removal, preheating temperature, baking temperature of the heat shrink sleeve, and the method of rolling out bubbles of the anchor flange all affect the quality of the anti-corrosion layer.