Grooved connection pipe fittings include two major categories of products: First, there are rigid joints, flexible joints, mechanical tee and grooved flange for sealing pipe fittings; There are elbow, tee, four-way, reducer, blind plate and so on.
The grooved connecting pipe has three parts: sealing rubber ring, clamp and locking bolt. The rubber sealing ring in the inner layer is arranged on the outer side of the connecting pipe, and tallies with the groove which is rolled in advance. The outer of the rubber ring is buckled with a clamp, and is fastened with two bolts. Because the rubber sealing ring and the clamps adopt the unique sealing structure design, the groove connecting parts have good sealing performance, and the sealing performance is enhanced with the increase of the fluid pressure in the tube.
What is the difference between a groove connection and a fitting connection?
The steel pipe is greater than DN100 with a trench connection to a multi-DN100 and a wire buckle connection (threaded connection) trench connection adopts groove-type pipe fittings need to be calculated separately and set the corresponding fixed thread connection. Setting of fixed quota considers its pipe fitting fittings to connect large-range tube thread connectivity, flange connection, socket connection, trench connection, etc. need to be used in three pass, size head, elbow, etc.
Problems Needing Attention in Installation of Grooved Pipe Fittings
At present, the pipeline using grooved pipe joints in various types of construction installation gradually popularized, its fast, reliable characteristics are being installed colleagues recognized in the field of fire engineering construction is also widely used. However, different ways of connecting rigid clamps, flexible clamps connection should pay attention to what problems, In the existing design, construction specifications have not been more detailed introduction, China’s existing product standards have been published in many provisions of industry standards for clamps, but also only involve manufacturing standards and related test content.
In the actual construction, the problems and solutions of pipe coupling with clamps are presented.
One, the rigid clamps installed in the DN ≤ 250 pipeline, according to the manufacturer’s product manual introduction, generally can get a satisfactory result.
II. The following installation details should be paid attention to in connection with flexible clamps on DN ≥ 300 pipelines:
- Quality of steel pipe:
The tolerances of the outer diameter, wall thickness uniformity and the non-roundness of the pipe at both ends of the pipes shall not exceed the national standards. When loading and unloading steel pipes, it is necessary to prevent deformation of the pipe mouth.
- Measurement and appearance inspection before pipe mouth pressure groove:
Before the nozzle pressure groove, should check whether the nozzle end face is perpendicular to the pipe center line, whether the tolerance of non-roundness of the nozzle exceeds the standard, whether burrs around the nozzle are eliminated and polished, such as the nozzle of non-round or deformed, must be removed.
3, pressure groove processing:
For long pipe grooving, supporting bracket must be set up and ball bearing supporting points are installed on the bracket to reduce the fluctuation of pipe rotation. Strict groove depth, groove depth must meet the requirements of the manufacturer’s instructions. During operation, the depth of the pressure groove should be mastered gradually, and the die should be replaced in time. After grooving, the zinc-plating thin skin that has been peeled off inside the pipe mouth should be removed readily and anti-corrosion treatment should be carried out. When handling, hoisting and loading, the pipe mouth pressure groove should be protected to avoid deformation.
- Appearance quality of approach clamp:
The manufacturing precision of large caliber clamps is affected by various factors because they are manufactured by ball milling cast iron sand mold. A sample examination of appearance should therefore be conducted, including the following items:
4.1 flexible clamps on the flat round diameter is too large too small are not qualified. Generally master the inner diameter of two clamps and the outer diameter of the steel pipe matching, the gap between the two clamp is about 2mm, no roundness can not exceed the standard, otherwise it should be repaired and installed.
4.2 The flange height and thickness of the clamps inserted into the pressure groove must conform to the manufacturer’s enterprise standards.
4.3 The radial deformation of the clamp itself can not exceed the standard.
5, the clamp installation should pay attention to:
5.1 clamp installation, especially the installation quality of flexible clamp, In addition to the above requirements: that is, pipe material, size, mouth deformation size, pressure groove quality and the quality of the clamp itself, size excess size, must also ensure that each piece of clamps into the groove.
5.2DN ≥ 300 and more large caliber flexible clamp installation should pay attention to:
5.2.1 Material and appearance inspection of rubber sealing ring:
Each manufacturer of rubber seal ring according to the use of different media, its manufacturing materials and formulations are different, but the installation unit must ask the production unit and its unit project life of the same product quality commitment and the physical and mechanical properties of rubber sealing ring test report, The appearance of the inspection should be no damage, no deformation, no air bubbles, impurities, cracks and uneven defects on the rubber sealing surface.
5.2.2 Installation of grooved pipe fittings:
A. Groove, hole with hand touch, eye observation for a week, can not have the remaining burr, damage, crack, and remove the remaining dirt around the mouth.
B. the rubber sealing ring is coated with lubricant on all sides and is installed at both ends of the steel pipe by hand. At this point to ensure that the tension around the rubber sealing ring is basically the same.
C. Two pieces of grooved pipe fittings, and the bolts are screwed symmetrically on both sides, so that the gap between each groove is basically equal. To be close to tightening and not in contact with the rubber seal ring is very close, with both hands to move the grooved pipe fittings, so that the entire pipe fittings and the seal ring preliminary contact uniform, observe the groove pipe pieces have been into the groove, and then symmetrical separately, successively tighten the bolts. If the sealing ring is wrinkled and protruding when fastening, it should be replaced.
5.2.3 must ensure that the groove pipe flange into the groove and then symmetrical fastening bolts on both sides. The “convex edge card into” refers to: located in the groove pipe convex edge and pipe groove depth of about 2mm or so of the protruding embedded should be flush with the mouth of the concave embedded after pressure groove. The finished product clamps sometimes appear convex thick, deformation is too large, and even the plane twist too big, the site can repair repair, can not repair only abandoned, another for a re-install. This requires on-site operators to observe one by one, basically meet the requirements of reloading, so as to avoid rework.
5.2.4 When using imported grooved pipe fittings and domestic pipe fittings, Must know in advance the manufacturer of the product is what standard, must be matched with the grooved pipe fittings pipe, otherwise, due to different standards, prone to a large area of unqualified pressure test, causing huge losses.