SU1298604A1 - Method of strength testing of lap joint of pipe with surface crack and strap - Google Patents

Abstract

The invention relates to tests for the cyclic strength of an overlap joint of a pipe and a lining and improves their performance by conducting tests during the period of propagation of a crack beyond the lining boundary by increased pressure. The pipe 1 with a crack 2 on the surface connected to the cover 3 is supplied with cyclically varying internal pressure, which is chosen from the ratio P Pjd + Sj / S,), where P is the internal pressure in the pipe; P is the operating pressure; 5 - the thickness of the lining, 5, - the thickness of the pipe. After the propagation of the crack 2 beyond the boundaries of the patch 3, the pressure in the pipe 1 is reduced to operating pressure, and the strength is judged by the time to failure. 1 IL. with (/)

Description

The invention relates to tests for the cyclic strength of the overlapping joint of a pipe and a lining.

The purpose of the invention is to increase the productivity of the tests by conducting tests during the period of propagation of a crack beyond the edges of the lining with increased pressure.

The drawing shows the test compound.

The joint consists of a pipe 1 with a thickness of 5, with a crack 2 having a length P.p to which a patch 3 is welded over a crack 2 with thickness b and length L |, the length of which is chosen from the condition

K 10

TTG

Where

To with

fracture toughness;

С - voltage in the pipe corresponding to internal pressure of R.

The method for testing the strength of the joint overlap of a pipe with a crack on its surface and an overlay is carried out as follows.

Requirement 1 creates a cyclically varying internal pressure selected from the ratio

P p d + Rj / s,)

where P is the operating pressure. After the propagation of the crack 2 beyond the boundaries of the patch 3, the pressure in the pipe 1 is reduced to the operational one and continued to be tested until the overlap joint is destroyed. On the strength of the lap joint of a pipe with a crack I.Gorn's editor

Compiled by Y. Matvienko Tehred M. Morgenthal

Order 880/44 Circulation 777 Subscription

VNIIPI USSR State Committee for Inventions and Discoveries 4/5, Moscow, Zh-35, Raushsk nab. 113035

Production and printing company, Uzhgorod, st. Project, 4

Noah on the surface and lining judged by the time of its destruction.

PRI me R. A steel pipe with a diameter of 500 mm, a wall thickness of 9 mm, containing a surface crack 50 mm long along the line forming the pipe, is welded with an overlap joint a 9 mm thick plate, 200 mm long and 80 mm wide. Strength tests are conducted by cyclically varying internal pressure of 80 atm. After 500 cycles the crack goes beyond the boundaries of the lining, after that the pressure in the pipe is reduced to ex-. operational (40 atm).

Claims (1)

Invention Formula A method for testing the strength of a joint overlap of a pipe with a crack on its surface and lining, which consists in creating a cyclically varying internal pressure in the pipe, and the strength of the joint is judged in time until its destruction. J different By the fact that, in order to increase productivity, after the crack extends beyond the lining limits, the pressure in the pipe is changed in accordance with the ratio R p. (hi) where P is the maximum pressure of the cycle until the crack extends beyond the lining} maximum pressure of the cycle after the crack extends beyond the lining} -.tube thickness, - lining thickness. R. 1 Proofreader A. Obruchar