JP2931337B2 - Piping line leak inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention inspects the presence or absence of leaks due to poor connection in a piping line composed of a relatively soft synthetic resin pipe such as polybutene, polyethylene, or cross-linked polyethylene. About the method.

(Prior Art) In recent years, in hot water supply / water supply pipes of high-rise houses, synthetic resin pipes such as polybutene and polyethylene having excellent heat resistance have been used instead of lead pipes.

Normally, in this type of piping line, after the completion of piping, to prevent leakage accidents due to poor connection, each terminal of the piping line is closed and 1,75 times the maximum actual working pressure of the transport fluid. A liquid pressure of about a degree was applied and left for 1 to 24 hours, and the presence or absence of a leak was inspected from a change in the pressure in the pipe.

(Problems to be Solved by the Invention) However, since synthetic resin pipes such as polybutene and polyethylene are relatively soft, when pressure is applied to a piping line composed of these synthetic resin pipes, the synthetic resin pipe expands with time. Therefore, it has been difficult to determine whether this pressure drop is due to expansion of the pipe diameter or leakage.

For this reason, the pressure drop due to the expansion of the synthetic resin tube is sometimes mistaken for a leak due to a poor connection.

The present invention solves the disadvantages of the conventional inspection method, and provides a method capable of reliably inspecting for the presence or absence of a leakage portion without the influence of a pressure drop accompanying expansion of a synthetic resin tube. is there.

(Means for Solving the Problems) According to the present invention, in a piping line composed of synthetic resin pipes, first, each end of the piping line is closed, and a primary primary pressure of 1,5 to 2,5 times the maximum actual working pressure of the transport fluid is obtained. Is applied for a predetermined time. Next, a secondary liquid pressure, which is substantially equal to the maximum actual working pressure of the transport fluid, is applied to the piping line, and the pressure drop over time is inspected.

(Action) When a primary liquid pressure of 1,5 to 2,5 times the maximum actual working pressure of the transport fluid is applied to the piping line, the pipe diameter expands, and then the secondary fluid pressure is approximately equal to the maximum actual working pressure of the transport fluid. The tube diameter does not expand when the next liquid pressure is applied. Therefore, if there is a pressure drop at this time, it is clear that a pressure drop has occurred due to leakage due to poor connection.

(Examples) Hereinafter, specific configurations of the present invention will be described in detail based on examples.

The inspection method of the present invention can inspect the presence or absence of a leak in a piping line made of a relatively soft synthetic resin tube such as polybutene, polyethylene, or cross-linked polyethylene. The present invention can also be applied to piping lines using synthetic resin pipes.

As a specific example, the maximum actual operating pressure is 10 kgf / cm.
The case of a piping line of synthetic resin pipe (outer diameter: 17 mm, wall thickness: 2,2 mm) made of polybutene for transporting hot water supply which is ² , will be described.

First, after piping is performed with a synthetic resin pipe made of polybutene, each end of the piping line is closed and air is vented from the piping line. Next, a water pressure of 1,75 times the maximum actual working pressure is applied to the piping line and maintained for 2 hours.

The primary liquid pressure load caused the synthetic resin pipe made of polybutene to expand, and the internal pressure of the pipe line decreased to 16.5 kgf / cm ² .

Next, the water pressure in the piping line was lowered to maintain the maximum actual working pressure of 10 kgf / cm ² , and the secondary liquid pressure was maintained for 1 hour while being loaded. At this time, although I connexion synthetic resin tube pressure drop the internal pressure was slightly contracted has 0,2Kgf / cm ² boosting,
Thereafter, no pressure drop was observed, and thus it was found that there was no fluid leakage due to poor connection.

In the above-described embodiment, the piping line of the synthetic resin pipe made of polybutene has been described. It can be set to about 2.5 times. At this time,
If the primary pressure is lower than 1.5 times the maximum working pressure, there may be a disadvantage that the pipe diameter expands when the secondary pressure is next applied to the piping line. If the primary pressure is higher than 2.5 times the maximum actual working pressure, the piping line may be damaged because it exceeds the allowable pressure of the piping line.

On the other hand, the holding time of the primary pressure and the secondary pressure can be appropriately set depending on the type of the synthetic resin pipe, the pipe diameter, the wall thickness, the on-site atmosphere temperature of the pipe construction, etc.
A few hours are sufficient.

(Effects of the Invention) As described in detail above, the present invention applies a primary liquid pressure of 1.5 to 2.5 times the maximum actual working pressure of the transport fluid to the piping line to expand the synthetic resin pipe. Then, a secondary liquid pressure that is approximately the same as the maximum actual working pressure of the transport fluid is applied, so that there is no influence of the pressure drop caused by the expansion of the synthetic resin pipe, Presence / absence can be easily and reliably detected.

Claims (1)

(57) [Claims] 1. A piping line comprising a synthetic resin pipe,
First, each terminal of the pipe line is closed, a primary liquid pressure of 1,5 to 2,5 times the maximum actual working pressure of the transport fluid is applied, and the primary liquid pressure is maintained for a predetermined time. A method for inspecting a leak in a piping line, comprising applying a secondary liquid pressure substantially equal to a working pressure and inspecting a pressure drop with time.