US2527068A - Ram packing - Google Patents

Description

L. MURRAY RAM PACKING Oct. 24, 1950 Filed May 3, 1946 Wm M . T T A Patented Oct. 24, 1950 Lynne Murray, Houston, Tex., assignor 150163 111 eron Iron- Works, Houston,'.Tex.,- a corporation of Texas Amine-admirer a; 1946; serial No.- 666,959

i 1 This invention relates in general to blow-out prevente'rs for use with oil well equipment and more particularly has reference to packing asseniblies for use in blow-out preventers. a The present invention is directed to packing assembliesfor blow-out preventer rams of the general type described in the U. S. Patent to Allen; No. 2,194,255. v Inthe drilling of. wells such as oil wells it is often necessary, especially in the case of deep wells; to provide a so-called blow-out preventer on the upper portion of the well head or casing. These devices generally comprise a pair of rams movabletowardsand away from each'other transyerselyof the casing. The meeting faces of the rams are shaped to fitabout tubing extending down through the casing into the well and said faces are usuallyfitted with resilientpacking suchas rubber to provide asealbetween the faces of the rams-and the-tubing. v W

Whenemploying blow-out preventers' of the type justmentioned, it; is necessary to pull up the tubing and lower the same while maintainingthe ramsof the blow-out preventer in seal ing position. Ithas-beenfound that upon Shift-,- ing the tubing while the blow-out preventer is in operative position, there is a tendency for the rubber packing to adhere to the tubing and be pulledthrough the opening in the plates for confining the packing with resultant damage to the packing. After such-action occurs often enough it will be found that the sealing face of the packing is torn away especially'adjacent the opening in the confining plate which seriously impairs the effectivenessof the sealb'etw'een the ram face and the tubing. v V L The principal object of-this invention a is to avoid the above pointed out disadvantages of the prior art.

Anotherobject of this invention is to provide apacking for blow-out preventers' whichis constructed to avoid extrusion through joints sealed by the same.

A further object of this invention is to provide a packing for blow-out preventers which comprises a relatively soft body portion having a relatively hard face portion for engaging the tubing sealed thereby.

With these and other objects in view, the present invention resides in the parts and combinations hereinafter set forth.

In order to facilitate an understanding of the present invention, reference is made to the accompanying drawings in which similar parts are indicated by similar reference characters.

2 chains. (01. zit-1e) Figure 1- is a perspective viewofa packing assembly element constructed according to the priorart: .l

Fig; 2 is a similar view with parts in section of a packing assembly element embodying thefeatures of the'present invention.

Fig. 3 is a fragmentary sectional view ofsa ram packing in engagement with atubeto be sealed against. .Y

A: conventional packing assembly of theugeneral type to which this invention-relates is shown in Fig. 1 of the drawings and comprises a packing body I having packing retainerclipsem bedded therein; These clips are in the, form" of rods embedded in the rearwardly extendingarms of the assembly andhaving rear oppositely facing end portions 2 adapted to be spread apart to be slipped-over a ram (not shown) andthen allowed-to move toward each other for engagement in- -openings in the opposite sides of the ram to hold the assembly in place thereon, allas set forth in the above mentioned Patent No. 2,194,255, and forward portions 3 projecting upwardly and downwardly through ,slots 4 in the packing retainer p1ates'5and6 disposed above and below the packing] Plates 5 and 6 are tied together by; suitable pins I, Plates 5 and 6 are provided with registeringsemi-circular cut-out portions; 8 whichareasizeto snugly receive atube or pipe extending down through the casing, The packmg} l is; similarly shaped when the rams are pressed towardeach other the packing assemblies snugly grasp the tubing. With'the plates- 5 and 6: engaging the tubing; the packing I ispressed aboutthetubing to form aseal; If as in the-usual construction; thepacking body I soft and flexible enoughto make it possible to spread the frea-rwa'rdly: extending arms apart enough to engage'them' with a ram, as above described; then when the tubing israised or lowered while the packing-is sealed about" the same the packin will adhere to the tubing and tend to be pulled or extruded between the tubing and the plate 5. This causes the portion of the packing adjacent the plate 5 to be torn away as indicated by reference character 9. This has been found to be true even if the edges of the contact face of the body, adjacent the plates 5 and 6, are bevelled as indicated at l I. After the packing is so damaged difficulty may be encountered in subsequently effecting a seal between the packing and the tubing, and in any event repetition of this extrusion and tearing action renders the packing use-v less in a relatively short time.

According to the present invention it has been found that damage to the packing can be avoided even when the tubing is raised while the packing is pressed against the same by the rams of the blow-out preventer by employing packing of special construction. As shown in Fig. 2 a packing assembly according to the present invention comprises a packing body la, of the conventional form and mainly of the usual resilient material, soft and flexible enough to permit the rearwardly extending arms to be spread apart in mounting the assembly on a ram as above described. Packing retaining clips in the form of rods are embedded therein the same as shown in Fig. 1. The rear portions of therods extend inwardly as pins 2a between the arms of the packing and front portions of the rods project as pins 3a through slots 4a in the packing retaining plates 5a and 6a. Pins la tie the plates 5a and 6:: together.

As illustrated in Fig. 2 the packing la of the present invention is 'unique'in that'it isformed of portions of different degrees of hardness. While the main portion is conventionally soft and flexible enough for the purpose above stated, the portion thereof that is pressed against the tubing to be sealed is of a hardness much greater than the remaining portion thereof.- This relatively hard portion is well bonded'to the softer body of sealing material. By forming the tube engaging portion I!) of the packing of a hard resilient material, said material does not adhere to the tube and is not extruded and sheared or cut as illustrated in the construction of Fig. 1.

an example when the packing is formed entirely of ordinary vulcanized rubber of a hardness approximately '70 durometer, a result similar to that shown in Fig. 1 is obtained. When however the packing is formed mainly of such rubber but-with a zone of rubber In of a hardness approximately 90 durometer interposed between the relatively soft rubber Ia, and and the tubing,-an effective sealbetween the packing Ia. and the tubing is obtained without the usual adherence and friction between the packing and the tubing. By virtue of the hardness and stiffness of the rubber of the zone ID the tendency toward extrusion is resisted very strongly, and in substance prevented. This enables the tubing to be pulled through the blow-out preventer without partially extruding the packing or damaging the packing as indicated in Fig. 1 of the drawings. In actual practice it has been found-that a packing constructed in the manner described will last several times as long as one of conventional construction.

Preferably, the edges of the contact face of the packing body are bevelled adjacent the plates 5a. andfia. to provide recesses in the body, as shown at Ila, rearwardly of thecontact faces of the plates. The bevels provide a space for the packing material to flow into during the initial stages of its compression. This insures contact between the plates and tubing before the packing material can be pressed into position between the plate and tubing which would, of course, cause it to be sheared or pinched off as the plates are moved by the rams into contact with the tubing.

While resilient and hard rubbers have been given as examples of the substances forming the packing of the present invention, it is to be under stood that various rubber containing compounds and other materials having desirable packing properties and being relatively soft and relatively hard may be used in conjunction with each other in the manner herein described.

From the foregoing description it will be appreciated that the present invention provides a packing assembly construction for blow-out preventerswhich avoids the prior art disadvantages.

In the foregoing specification and in the appended claims, reference to rubber is intended to cover both natural and synthetic rubber and rubber-likecompounds'. ,1

Having. described my invention, I claim:

1. A packing assembly for blow-out preventers comprising two spaced, parallel, rigid retainer plates, a body-of resilient sealing materialof a hardness of about '70 durometer bonded between the plates, the plates and body having contact faces with a semi-circular cut-a-w'ay centrally thereof adapted to receive a tubing, a zone of resilient material of about 90 durometer formed as a part of the body and bonded to the softer portion of the body and to the plates, said zone providing the entire contact face in the cut-a-way.

2. A packing assembly for blow-out preventers comprising two spaced, parallel, rigid retainer plates, a body of resilient sealing material of a hardness of about durometer bonded between the plates, the plates and body having contact faces with a semi-circular cut-a-way centrally thereof adapted to receive a tubing, a zone of resilient material of about durometer formed as a part-of the body and bonded to the'softer portion of the body and to'the plates, said zone providing the entire contact face in the cut-away, said body having bevelled edges adjacent the plates and along its contact face providing recesses in the body rearwardly of the contact faces of the plates.

I LYNNE MURRAY.

REFERENCES CITED The following references are of record in the file of this patent: j

' UNITED STATES PATENTS Benson June 4, 1946

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