Valves and similar flow control equipment are normally bolted into high pressure systems via flanges.

In order to test such equipment it is normal to bolt the equipment to test apparatus via a flanged connection.

In the case of large valves for use in the oil and chemical engineering industries this can take several hours involving the use of a large number of bolts which have to be individually tightened to the desired torque in a specified order. A similar problem arises in dis¬ mounting the valves.

The present invention aims, at least in its pre¬ ferred embodiments, to facilitate the mounting and dismounting of the equipment to be tested. According to one aspect of the present invention there is provided a test apparatus for pressure testing equipment having a flange, which test apparatus com¬ prises:

(a) an upwardly extending cylindrical housing; (b) a piston slidably mounted in said cylindrical housing;

(c) means for introducing hydraulic fluid into a chamber beneath said piston; and

(d) retaining means for limiting separation of a flange on the equipment to be tested relative to said upwardly extending cylindrical housing so that said piston may be pressed into sealing engagement against said flange by admitting hydraulic fluid to said cham¬ ber. Optional features of the present invention are set

out in Claims 2 to 8.

The present invention also provides a method of pressure testing equipment having a flange, which method comprises the steps of: (a) moving said flange into general alignment with the upwardly extending cylindrical housing of a test apparatus in accordance with the present invention;

(b) applying two or more retaining members to limit separation of said flange and said upwardly extending cylindrical housing;

(c) introducing hydraulic fluid into said chamber to urge said piston into sealing equipment with said flange, and

(d) introducing hydraulic fluid into said equipment o test the integrity thereof.

For a better understanding of the invention refer¬ ence will now be made, by way of example, to the accom¬ panying drawings, in which:-

Fig. 1 is a side view, partly in section, of one embodiment of a test apparatus in accordance with the present invention testing a blow out preventer (BOP) ;

Fig. 2 is a view along line II-II of Fig. 1; and

Fig. 3 is a view, to an enlarged scale, along line III-III of Fig. 1. Referring to Fig. 1 of the drawings, there is shown a test apparatus which is generally identified by refer¬ ence numeral 10. A BOP 12 is mounted on the test appara¬ tus 10.

The BOP 12 comprises an upstanding tubular member 14 which supports left and right rams 15 in cylindrical housings 16. The rams are driven by hydraulic pressure which is applied through the lines 18 so that the rams are able to close toward the annular space. The rams 15 are profiled to fit around a drill pipe 20 to inhibit fluid flow in the annulus between the drill pipe 20 and the bore 17.

The BOP is provided with a bottom flange 22 which enables connection to the wellhead equipment connected to the casing of a well. The flange 22 can be quite large and can typically measure 600-900mm (two or three feet) in diameter, is quite thick, often several inches in thickness, and typically requires as many as 16 to 24 large bolts for installation. Moreover, the bolts are quite long, difficult to handle because of their size, and require threading. The bolts are threaded to relat¬ ively large nuts which require power driven nut drivers, and the last few turns must be applied with a torque wrench having a controlled amount of torque applied through the wrench to fasten the nuts on the bolts. The nuts must be tightened in a particular sequence around

the flange. This procedure takes several hours to exec¬ ute to assure that the flange connection is properly made.

• The test apparatus 10 is mounted on a skid 24 and comprises an upstanding cylindrical housing 26. The upstanding cylindrical housing 26 is supported on a bottom plate 28 which is centred on the skid 24. A piston 32 is slidably mounted in the upstanding cylin¬ drical housing 26. The lower surface 33 of the piston 32, the top surface of the bottom plate 28 and the upstanding cylindrical housing 26 together define a chamber 30. The piston 32 can be moved in response to the introduction of hydraulic fluid into the chamber 30, and the piston 32 is sealed by appropriate seal rings around its periphery.

The upstanding cylindrical housing 26 terminates at a circular flange 34 which does not require bolt holes for fastening. The circular flange 34 terminates at a face 36 which confronts the bottom flange 22 of the BOP 12.

The two flanges 22, 34 are aligned by two identical guide rings 40. Each guide ring 40 is semicircular, and comprises a lower lip 42 which extends radially inwardly and is parallel to an upper lip 44 which also extends radially inwardly. Each guide ring 40 is positioned by means of a hydraulically powered piston and cylinder arrangement 48.

Whilst two guide rings each subtending 180° may be used a larger number of guide rings each subtending a smaller angle might also be used.

Each piston and cylinder arrangement 48 is mounted by a pivot to a post 50 attached to the skid 24. Fur¬ ther, left and right angle irons 52 and 54 serve as guide rails (Fig. 2). A pivot connection 56 enables each guide ring 40 to connect with the piston rod extending

from its respective piston and cylinder arrangement 48.

As shown in Fig. 3, a high pressure hydraulic fluid supply line 60 communicates with chamber 30 via a pas¬ sage 62. In addition there is a similar hydraulic fluid supply line 70 which communicates with the top 66 of the piston 32 via a passage 72.

The top 66 of the piston 32 is provided with two concentric grooves 65a, 65b for receiving gasket rings of different diameters. In use, a gasket ring 64 is placed in the appropri¬ ate groove in the top 66 of piston 32. The BOP 12 is then lowered into position by an overhead hoist and the guide rings 40 applied as shown in Fig. 1.

Hydraulic fluid is then admitted to chamber 30 to raise the piston 32 slightly. The positioning of gasket ring 64 in corresponding grooves in the top 66 of the piston 32 and the bottom flange 22 of the BOP is then checked and further hydraulic fluid admitted to chamber 30 to achieve the desired seal. Hydraulic fluid is then introduced through hydrau¬ lic fluid supply line 70 until the desired pressure is achieved. The supply of hydraulic fluid is then cut-off and the pressure inside the BOP 12 measured over the requisite period of time. The test apparatus is especially beneficial in that the BOP can be mounted and dismounted comparatively quickly.

If desired, alternate sets of guide rings 40 can be used where each of the several sets have different diameters or different thicknesses to accommodate flanges of different diameter or thickness. Some initial gap is left between the two flanges which are captured in the guide rings 40, but this gap can be reduced by merely extending the piston 32. Such movement is permit- ted because the hydraulic fluid supply line 70 extends

through a slot 71 formed in the upwardly extending cylindrical housing 26. The hydraulic fluid supply line 70 can therefore move upwardly and downwardly with the piston 32. Whilst the preferred embodiment relates to the pressure testing of a BOP, any form of apparatus having a flange may be tested.

The test apparatus 10 shown in Fig. 1 comprises a skid 24. That is especially helpful in a rental facility such as the yard at a BOP rental store. An alternate embodiment can be readily achieved merely by anchoring the skid 24, for example beneath an overhead crane so that large valves having flanges can be moved to the facility for testing at a manufacturing plant. In another embodiment the circular flange 34 is provided with holes or, perhaps even more conveniently, arcuate slots to receive extending studs permanently affixed to some industry standard flanges.

In this particular instance, the protruding studs merely extend through the circular flange 34 on the housing, and the two clamp rings 40 are preferably deleted while the nuts are run up the studs into contact with the circular flange 34 and lightly but uniformly tightened. It should be noted that it is not necessary to tighten the nuts to the full operating torque and that only a light uniform tightening is required.

If the BOP under test is provided with a pressure test point hydraulic fluid may be introduced into the

BOP through this test point rather than through hydrau- lie fluid supply line 70 which is redundant in such an embodimen .

It will be noted that in the embodiment described with reference to the drawings the bottom flange 22 and the circular flange 36 need not be of the same diameter.