Method of forming a blowout preventer body

A method of manufacturing a blowout preventer body includes the steps of: providing more than one billet; forming a first billet to form a first portion of the blowout preventer body; forming a second billet to form a second portion of the blowout preventer body; and welding the billets to form the blowout preventer body.

FIELD

The present application relates to a method of forming a blowout preventer body using forging techniques.

BACKGROUND

Many of the ram-type blowout preventers developed over the past 60 to 80 years utilize rectangular shaped ram blocks that travel in a horizontal direction from opposite sides of the blowout preventer to meet approximately in the middle of a wellbore. The rectangular shape, with square or semi-circular sides, has provided a means to keep the height and weight of the ram blocks reasonable as compared to a circular shaped block. In order to form the gates for the rectangular ram blocks, sand casting is commonly used to manufacture the blowout preventer bodies.

SUMMARY

There is provided a method of manufacturing a blowout preventer body. The method comprises the steps of: providing more than one billet; forging a first billet to form a first portion of the blowout preventer body; forging a second billet to form a second portion of the blowout preventer body; and welding the billets to form the blowout preventer body.

DETAILED DESCRIPTION

A blowout preventer body considered to be Prior Art is illustrated inFIG. 1throughFIG. 4. Referring toFIGS. 1-2, a typical blowout preventer body50is shown. Blowout preventer body50has a rectangular ram block opening52. Body50is constructed by casting steel around a sand core.FIGS. 1-2show a single gated embodiment of blowout preventer body50. Referring toFIG. 3, a double gated embodiment blowout preventer54is shown. Referring toFIG. 4, a blowout preventer body56that is an embodiment of the prior art is shown. Blowout preventer body56includes two single gated blowout preventer bodies50welded together. The one piece casting methods used to manufacture any of blowout preventer bodies50fromFIGS. 1-4are generally expensive and often lead to imperfections that effect the usefulness and safety of blowout preventer bodies50,54, and56. The cast steel method also has practical limitations as to the number of gates that can be formed from one body due to the weight and complexity of the sand core required to form each rectangular internal profile.

A blowout preventer body generally identified by reference numeral70, will now be described with reference toFIG. 5 through 37.

Referring toFIG. 27, a blowout preventer body70is shown consisting of a first billet72and a second billet74. First billet72has been formed as a first portion76of body70, and second billet74has been formed as a second portion78of body70. In the description below, it will be understood that billets72and74may be formed to have the desired characteristics by any suitable process, such as forging, machining, or a combination thereof. In the example shown, first portion76is the top portion of body70, while second portion78is the bottom portion of body70.

Referring toFIGS. 5-7, different views of first billet72are shown. Referring toFIG. 5, first billet72consists of a pipe passageway86and a first surface88. Pipe passageway86may be circular as shown, in order to allow a pipe (not shown) to be passed through or positioned within pipe passageway86. Referring toFIGS. 5-7, a first gate portion94has been formed out of first surface88, as shown. First gate portion94is provided with a seat92, a base93and sidewalls95. Seat92may be provided as part of forged first billet72, or may be provided as a replaceable part. Referring toFIGS. 8-10, first surface88of first billet72has been machined to form weld preparation surfaces96and contact tips98.

Referring toFIGS. 11-13, different views of second billet74are shown. Referring toFIG. 11, second billet74consists of a pipe passageway100and a first surface102. Pipe passageway100is shown to be circular, in order to allow a pipe (not shown) to be passed through or positioned within pipe passageway100. Referring toFIGS. 11-13, a second gate portion106has been formed out of first surface102, as shown. Second gate portion106is provided with a seat108, a base109, and sidewalls110. Seat108may be provided as part of forged second billet74, or may be provided as a replaceable part. Referring toFIGS. 14-16, second billet74has been further machined to form weld preparation surfaces112and contact tips114out of first surface102and gate grooves116out of base surface109and seat108. Gate grooves116are provided to allow fluid to flow behind a ram block (not shown) when the ram block is moved to close passageway100in the event of a blowout. Gate grooves116define skids118, skids118being the material remaining from base109and seat108after machining. Alternatively, skids118may be provided as replaceable parts that can be easily replaced and secured into second billet74using conventional methods.

Referring toFIG. 22, first gate portion94formed in first surface88of first billet72is positioned adjacent to second gate portion106formed in first surface102of second billet74. Contact tips98and114are aligned and allow first billet72to be positioned on second billet74. Referring toFIG. 25, first and second billets72and74, respectively, have been welded together to form blowout preventer body70. The welding of first and second billets72and74, respectively, together is accomplished by forming welds of metal120between weld preparation surfaces96and112. The selection of the type of welding used will be influenced by standards created by regulatory organizations for pressure containing equipment, for example a qualified material specific full penetration weld. When first and second billets72and74, respectively, are welded together, first gate portion94and second gate portion106form a gate cavity122of blowout preventer body70. Gate cavity122is designed to hold a ram block, or any other blowout preventing pipe-shearing/sealing devices known in the art. Gate cavity122is constructed to have a rectangular cross section82, although other shapes of cross sections are possible with this method of manufacture. While rectangular ram blocks are described, it will be understood that the cross-section of either the block or gate may have some variance from a rectangle, such as rounded corners, substantially equal sides, projections/depressions, etc. as will be recognized by those familiar with blowout preventers. Furthermore, the techniques described herein can be used to form blowout preventers with different gate shapes other than rectangles. Referring toFIGS. 31 and 32, respectively, blowout preventer bodies150and160, respectively, may be constructed to have a gate cavity152that has a semi-circular cross section84. Cross sections82and84are both designed to be fitted with appropriately-shaped ram blocks (not shown).

Referring toFIG. 27, blowout preventer body70has been machined after welding first and second billets72and74, respectively, together. In the example shown inFIG. 27, contact tips98and114(shown inFIG. 22), and sidewalls95and110have been machined down, although other surfaces of body70may be machined as well. Body70must be machined upon welding, in order to qualify welds120as full penetration welds. Machining may be accomplished using machining processes known in the art, such as broaching and shaping, although other methods may be devised.

Referring toFIGS. 17-18, an intermediate billet124is provided. A first gate portion126has been formed out of a first surface128, first gate portion126being formed identical to first gate portion94of first billet72as shown inFIGS. 6-7. A second gate portion130has been formed out of a second surface132of intermediate billet124, second gate portion130being formed identical to second gate portion106of second billet74as shown inFIGS. 12-13. Second surface132is positioned parallel to first surface128. Referring toFIG. 19, first and second gate portions126and130, respectively, have been machined in an identical fashion as first and second gate portions94and106, respectively, have been machined inFIGS. 9 and 15, respectively. Referring toFIG. 21, intermediate billet124is positioned between first and second billets72and74, respectively, forming a blowout preventer body134. First gate portion126in first surface128of intermediate billet124is oriented toward second gate portion106in first surface102of second billet74and second gate portion130in second surface132of intermediate billet124is oriented toward first gate portion94in first surface88of first billet72. Referring toFIG. 20, two intermediate billets124are positioned in between first and second billets72and74, respectively, in the same orientation as described above forFIG. 21, forming a blowout preventer body136, that has each one of first gate portions94and126oriented towards one of second gate portions106and130.

Referring toFIGS. 23-24, intermediate billets124fromFIGS. 20-21, respectively have been welded together using welds of metal120. The welding is done in an identical fashion as that described forFIG. 25. In this manner, each combination of one of first gate portions94and126combined with one of second gate portions106and130form more than one gate cavity122in blowout preventer bodies134and136. It will be understood that blowout preventer bodies134and136can be machined in a fashion identical to that described for blowout preventer70inFIG. 27.

Referring toFIG. 32, blowout preventer body160with a gate cavity152with semi-circular cross section84is shown after full penetration welding has been completed. Referring toFIG. 30, blowout preventer body160is shown before the final machining step to complete the full penetration weld. Referring toFIG. 31, blowout preventer body150with two of gate cavities152with semi-circular cross sections84are shown after full penetration welding has been completed. It should be understood that any number of gate cavities152,122may be constructed on any of the above described embodiments. Referring toFIG. 29, blowout preventer body150is shown before the final machining step to complete the full penetration weld. Referring toFIG. 28, a blowout preventer body170is shown before the final machining step to complete the full penetration weld.

Referring toFIGS. 34 and 35, blowout preventer bodies150and160are shown in a completed state. Bodies150and160may be machined and heat treated or otherwise treated to relieve the stresses that may have been created during welding if necessary.

It will be understood that the steps described herein are applicable to blowout preventers that only require two sides to be welded, which is shown in the embodiments described above, as well as blow out preventers that require all four sides to be welded with welds120, as shown inFIGS. 36 and 37. Once properly processed, normal machining routines may be used to finish the blowout preventer180as required.

The term “billet” commonly refers to a blank steel product that has been prepared for further processing, such as forging and machining. In this application, the term is used to refer to any product that has been sufficiently processed to be used in the method described herein.

Referring toFIG. 6, first billet72is provided, first billet72having had first gate portion94formed in first surface88. As stated above, forming may include processes such as forging, machining, or a combination thereof. Referring toFIG. 12, second billet74is provided, second billet74having had second gate portion106formed in first surface102. Both of first and second billets72and74, respectively, are forged using hot-working methods. A clean billet (not shown) is initially provided, the clean billet being free from sand and slag inclusions inherent in steel cast processes. The billet is then hot worked into the desired shape by pressing and hammering with shaped dies. The hot working of the billet improves the material properties by producing a finer flowing grain structure as the material is formed into its shape. The result, after appropriate heat-treating processes if necessary, is a superior material, free from defects.

Referring toFIGS. 9 and 10, respectively, first and second billets72and74are machined to prepare each for welding together to form blowout preventer70(shown inFIG. 22). Referring toFIG. 9, machining processes form weld preparation surfaces96, contact tips98, and shape sidewalls95into their desired shape. Referring toFIG. 15, machining processes form weld preparation surfaces112, contact tips114, gate grooves116, and shape sidewalls110into their desired shape. Alternatively, replaceable skids118may be added in place of the remaining base109material surrounding gate grooves116. Because base109is prone to wear, it is desirable to afford a user the option to replace skids118if they wear out.

Referring toFIGS. 17 and 19, if more than one gate cavity122(shown inFIG. 22) is required for blowout preventer70, one or more intermediate billets124may be created and used. Intermediate billet124may be forged and machined in a fashion similar to that used above for forming and machining first and second gate portions94and106, respectively, of first and second billets72and74(shown inFIG. 22). First gate portion126may be forged and machined from first surface128, while second gate potion130may be forged and machined from second surface132. First and second gate potions126and130, respectively, are completed to have a top profile138and a bottom profile139identical with first and second gate portions94and106, respectively.

Referring toFIG. 22, for blowout preventer70, only one gate cavity122is required. First billet72is first assembled with second billet74as shown, so that contact tips98and114hold first and second billet72together in place for welding. First and second gate portions94and106, respectively, are now oriented together to form gate cavity122. Referring toFIG. 25, welds of metal120are then placed between weld preparation surfaces96and112, such that first and second billets72and74, respectively, are welded together. After appropriate machining and stress relieving, such as by heat treating blowout preventer70, blowout preventer70is allowed to cool, and further machining of blowout preventer70can take place. Referring toFIG. 26, positions140indicate the areas of blowout preventer70that requires further machining in the next step, and positions142indicate the areas that are optional for further machining. Referring toFIG. 27, contact tips98and114(shown inFIG. 25), are machined down to complete the required full penetration weld, and optional sidewalls95and110machined down.

Referring toFIG. 21, if an additional gate cavity122is required for the completed product, then intermediate billet124is prepared and assembled with first and second billets72and74, respectively as shown. First gate portion94of first billet72is oriented with second gate portion130of intermediate billet124to define gate cavity122. Second gate portion106of second billet74is oriented with first gate portion126of intermediate billet124to define gate cavity122. If still more gate cavities122are required, then additional intermediate billets124may be assembled in between first and second billets72and74, respectively, such that they are oriented in a similar fashion as described above. Blowout preventer134may then be completed by welding, appropriate stress relieving and machining, as described above for blowout preventer70.

Referring toFIG. 32, the above described process can be modified to create blowout preventer160having gate cavity152that has semi-circular cross section84. The product can be completed using the above-described process.

Once blowout preventer70is completed, body70is free from defects and far superior to the steel cast body blowout preventers used in the prior art. Alterations can be made to any of the above described embodiments, such as addition of threaded stud holes, hydraulic fluid flow holes, and outlet additions, to name a few examples.

The weld configurations shown in this document are only one way used to achieve the fabrication of the above-described blowout preventer bodies. The welds may be of different configurations and locations to arrive at the same net result. It should be understood that one skilled in the art would be able to adjust the weld positions and shapes, as the process could essentially net the same result.

Another distinct advantage to the method described here is the access to the internal rectangular cavity prior to welding the pieces together. In this component stage, additional machining may be done to prepare the body to accept replaceable parts such as seats and skids, which typically wear with usage. Internal machining processes are costly, difficult and in some cases, impossible when the body is formed in one piece. In the component stage however, all machining processes are viable due to access to all surfaces.

It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope defined in the Claims.