At present, the grooved pipe joint connection method is gradually promoted in various types of building installations. Its fast and reliable characteristics are being recognized by colleagues in the installation industry, and it is also widely used in fire protection engineering construction. However, what problems should be paid attention to when connecting rigid clamps and flexible clamps with different connection methods?
1. Install the rigid clamp on the DN≤250 pipeline according to the product manual provided by the manufacturer. Generally, satisfactory results can be obtained.
2. When connecting flexible clamps on DN≥300 pipelines, pay attention to the following installation details:
1) Quality of incoming steel pipe:
The tolerances of the outer diameter, wall thickness uniformity, and out-of-roundness of the pipe ends of the incoming steel pipe cannot exceed the standard requirements. When loading and unloading the steel pipe, it is necessary to prevent the deformation of the nozzle.
2) Measurement and visual inspection of pipe end before pressing groove:
Before the pipe end is grooved, check whether the end face of the nozzle is perpendicular to the center line of the pipe, whether the tolerance of the out-of-roundness of the nozzle exceeds the standard, and whether the burrs around the nozzle are removed and polished, such as the out-of-roundness or deformation of the nozzle , It must be removed.
3) Press groove processing:
For long steel pipe pressing grooves, support brackets must be installed, and ball bearing support points are installed on the brackets to reduce the fluctuation of pipe rotation during groove pressing. Strictly press the groove depth, which must meet the requirements of the product manufacturer’s instructions. During operation, attention should be paid to the rate at which the groove depth is gradually reached, and the mold that exceeds the service life should be replaced in time. When carrying, hoisting, loading and unloading the finished pipes, the pressure groove of the pipe mouth should be protected to avoid deformation.
4) Appearance quality of approach clamp:
Since large-diameter clamps are manufactured by ball milled cast iron sand molds, the manufacturing accuracy is affected by various factors. Therefore, the appearance should be sampled
5) Matters needing attention when installing the clamp:
The installation quality of the clamp, especially the installation quality of the flexible clamp, depends on the above-mentioned requirements: that is, the material of the pipe, the shape size, the deformation of the nozzle, the quality of the pressure groove, the quality of the clamp itself, and the size Ensure that all clamps are inserted into the groove.
6) Attention should be paid to the installation of large-caliber flexible clamps with DN≥300 and above:
Inspection of the material and appearance of the rubber sealing ring: The rubber sealing ring of each manufacturer varies according to the medium used, and its manufacturing material and formula are different, but the installation unit must ask the manufacturer for the same product quality commitment and rubber seal as its unit engineering service life The physical and mechanical performance test report of the ring should be free from damage and deformation in appearance inspection. Bubbles, impurities, cracks, and uneven defects on the rubber sealing surface are not allowed.
3 Installation of grooved pipe fittings:
a. Touch the grooves and holes by hand and observe with eyes for a week. There should be no remaining burrs, breakages, or cracks.
b. Lubricant is spread around the rubber sealing ring and then clamped on both ends of the steel pipe by hand. At this time, ensure that the tension around the rubber sealing ring is basically the same.
c. Two pieces of grooved pipe fittings, tighten the bolts symmetrically on both sides, so that the gap between each groove is basically equal. When it is close to tighten and not in close contact with the rubber seal ring, use both hands to rotate the grooved pipe fittings to make the entire pipe and the sealing ring evenly contacted. Observe that each piece of the grooved pipe fitting has entered the groove, and then tighten the bolts symmetrically and successively. . When tightening, the sealing ring is found to be wrinkled and raised, and the sealing ring should be replaced.
4. It is necessary to ensure that the convex edge of the grooved pipe fits into the groove and then tighten the bolts symmetrically on both sides.
This “knocked-in” means that the protruding embedment located on the protruding edge of the grooved pipe fitting and having the same height as the depth of the pipe groove should be flush with the concave embedding that appears after the nozzle is pressed. The flange of the finished clamp sometimes appears too thick, deformed, or even twisted too much. If it can be repaired on site, it can be repaired. If it cannot be repaired, it can only be discarded and replaced with another. This requires on-site operators to observe and inspect one by one, and basically meet the requirements before installing to avoid rework.
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