Pipe testing apparatus and method

1 . An apparatus for testing rings cut from pipes, comprising:

a plurality of test chamber sections which, when placed together, define a test chamber for receiving the ring to be tested, the test chamber sections comprising at least a first test chamber section defining a first inner face of the test chamber and a second test chamber section defining an opposed second inner face of the test chamber, the first and second inner faces defining annuli arranged to contain the ring to isolate the inside of the ring from the outside;

means for clamping the test chamber sections together to form the chamber;

a fluid inlet port in one of the chamber sections to allow a pressurized fluid to be admitted to the chamber outside the ring when received in the chamber; and

one or more sensors for measuring strain and deformation of the ring and fluid pressure, wherein the annuli are aligned with one another, are wider than the wall thickness of the ring to be tested, and are entirely flat.

2 . The apparatus of claim 1 , wherein the annuli are coated with lubricant.

3 . An apparatus as claimed in claim 1 , wherein the annuli are honed.

4 . The apparatus of claim 1 further comprising:

a pressurization system for providing the pressurized fluid to the fluid inlet port, wherein the pressurization system comprises an accumulator.

5 . The apparatus of claim 1 further comprising:

a sump for collection of any pressurized fluid that leaks to the inside of the ring from the outside.

6 . The apparatus of claim 5 further comprising a pump for recycling the pressurized fluid from the sump.

7 . The apparatus of claim 1 , wherein the annuli comprise one or more radial grooves and/or one or more projections.

8 . The apparatus of claim 7 , wherein the grooves/projections are spaced from one another around the annuli.

9 . The apparatus of claim 1 , wherein the annuli are polished.

10 . A method of testing a ring cut from a pipe, the method comprising:

a. cutting the ring from the pipe, the ring having end faces;

b. fitting attachments to measure the strains and deformations of the ring;

c. fitting the ring into an-apparatus, the apparatus including:

a plurality of test chamber sections which, when placed together, define a test chamber for receiving the ring, the test chamber sections comprising at least a first test chamber section defining a first inner face of the test chamber and a second test chamber section defining an opposed second inner face of the test chamber, the first and second inner faces defining annuli arranged to contain the ring to isolate the inside of the ring from the outside;

means for clamping the test chamber sections together to form the chamber:

a fluid inlet port in one of the chamber sections to allow a pressurized fluid to be admitted to the chamber outside the ring when received in the chamber; and

one or more sensors for measuring strain and deformation of the ring and fluid pressure, wherein the annuli are aligned with one another, are wider than the wall thickness of the ring to be tested, and are entirely flat;

wherein the fitting into the apparatus includes the first inner face against a first end face of the ring and the second inner face against a second inner face of the ring; and

d. applying pressure using the apparatus and recording and deformation measurements.

11 . The method of claim 10 , wherein an inner diameter of each annuli is 5 to 10 cm smaller than an inner diameter of the ring to be tested and an outer diameter of each annuli is 5 to 10 cm larger than an outer diameter of the ring to be tested.

12 . A method of testing a ring cut from a pipe, the method comprising:

a. cutting the ring from the pipe;

b. fitting attachments to measure the strains and deformations of the ring;

c. fitting the ring into an apparatus, the apparatus comprising:

a plurality of test chamber sections which, when placed together, define a test chamber for receiving the ring, the test chamber sections comprising at least a first test chamber section defining a first inner face of the test chamber and a second test chamber section defining an opposed second inner face of the test chamber, the first and second inner faces defining annuli arranged to contain the ring to isolate the inside of the ring from the outside;

means for clamping the test chamber sections together to form the chamber;

a fluid inlet port in one of the chamber sections to allow a pressurized fluid to be admitted to the chamber outside the ring when received in the chamber; and

one or more sensors for measuring strain and deformation of the ring and fluid pressure, wherein the annuli are aligned with one another, are wider than the wall thickness of the ring to be tested, and are entirely flat; and

d. applying pressure using the apparatus and recording the strain and deformation measurements.

13 . The method of claim 12 , wherein the ring comprises substantially parallel end faces that are each provided with a sealing element.

14 . The method of claim 13 , wherein the end faces are grooved for receiving the sealing elements.

15 . The method of claim 13 , wherein the sealing elements are resilient.

16 . The method of claim 13 , wherein the sealing elements comprise O-rings or lip seals.

17 . The method of claim 13 , wherein D/T>25, where D is the outer diameter of the ring and T is the wall thickness of the ring.

18 . The method of claim 12 , wherein the ring comprises substantially parallel end faces that are entirely flat.

19 . The method of claim 12 , wherein the end faces omit any sealing element.