Stay rod assembly

Abstract

A stay rod assembly for reciprocating pump assembly is disclosed. The reciprocating pump assembly includes a power section having a power source to reciprocate a plunger. A cylinder section has a chamber to receive the reciprocating plunger from the power section. The stay rod assembly secures the cylinder section to the power section. The stay rod assembly includes a stud and the sleeve. The stud has a first end, a second end, a middle portion extending between the first end the second end, and a shoulder between the first end and the middle portion. The sleeve surrounds the stud and has a first loading end adjacent the shoulder, and a second loading end adjacent the second end of the stud. The sleeve is configured to be pre-compressed and to pre-tension the stud for reducing cycling stresses.

What is claimed is: 
     
         1 . A stay rod assembly comprising:
 a stud having a first end and a second end, a middle portion extending between the first end and the second end, and a shoulder between the first end and the middle portion; and   a sleeve surrounding the stud, the sleeve having a first loading end adjacent the shoulder and a second loading end adjacent the second end of the stud, wherein the sleeve is configured to be pre-compressed and to pre-tension the stud for reducing cycling stresses.   
     
     
         2 . The stay rod assembly of  claim 1 , wherein the middle portion between the shoulder and the second end further comprises a plurality of fluted channels for reducing a cross sectional area of the middle portion. 
     
     
         3 . The stay rod assembly of  claim 1 , wherein the first end of the stud is secured to a power section of a reciprocating pump and the second end of the stud is secured to a cylinder section of the reciprocating pump. 
     
     
         4 . The stay rod assembly of  claim 3 , wherein the first end is threaded and is fastened onto the power section of the reciprocating pump. 
     
     
         5 . The stay rod assembly of  claim 3 , wherein the second end is threaded to receive a nut. 
     
     
         6 . The stay rod assembly of  claim 3 , wherein the first loading end of the sleeve is pressed against the power section of the reciprocating pump when the first end of the stud is secured to the power section and the second loading end of the sleeve receives a fastener tightening a flange of the cylinder section pressed against the sleeve. 
     
     
         7 . The stay rod assembly of  claim 6 , wherein the fastener on the second end of the stay rod compresses the sleeve by a predetermined distance. 
     
     
         8 . The stay rod assembly of  claim 7 , wherein the predetermined distance is between about 0.02 inches to about 0.05 inches. 
     
     
         9 . The stay rod assembly of  claim 1 , further comprising a first stress release groove between the first end and the shoulder, and a second stress release groove between the middle portion and the second end, wherein the first stress release groove and the second stress release groove each includes a curved cross section. 
     
     
         10 . The stay rod assembly of  claim 1 , wherein the sleeve further comprises at least one visual groove indicating a correct orientation for assembling the sleeve onto the stud. 
     
     
         11 . The stay rod assembly of  claim 1 , wherein the stay rod assembly experiences cycling stresses having a maximum stress, a minimum stress, and a difference between the maximum stress and the minimum stress, wherein the difference is no more than about 20% of the maximum stress. 
     
     
         12 . A reciprocating pump assembly comprising:
 a power section having a power source to reciprocate a plunger;   a cylinder section having a chamber to receive the reciprocating plunger; and   a stay rod assembly securing the cylinder section to the power section, the stay rod assembly comprising:
 a stud having a first end, a second end, a middle portion extending between the first end and the second end, and a shoulder between the first end and the middle portion; and 
 a sleeve surrounding the stud, the sleeve having a first loading end adjacent the shoulder and a second loading end adjacent the second end of the stud, wherein the sleeve is configured to be pre-compressed and to pre-tension the stud for reducing cycling stresses. 
   
     
     
         13 . The reciprocating pump assembly of  claim 12 , wherein the middle portion between the shoulder and the second end further comprises a plurality of fluted channels extending at least partially therebetween. 
     
     
         14 . The reciprocating pump assembly of  claim 12 , wherein the first end of the stud comprises threads for fastening onto the power section of the reciprocating pump, and the second end of the stud comprises threads to receive a nut. 
     
     
         15 . The reciprocating pump assembly of  claim 12 , wherein the first loading end of the sleeve abuts the power section of the reciprocating pump when the first end of the stud is secured to the power section and the second loading end of the sleeve abuts the cylinder section. 
     
     
         16 . The reciprocating pump assembly of  claim 15 , further comprising a fastener on the second end of the stay rod to compress the sleeve by a predetermined distance. 
     
     
         17 . The reciprocating pump assembly of  claim 12 , further comprising a stress release groove extending at least partially around the stud at a position between the first end and the shoulder. 
     
     
         18 . The reciprocating pump assembly of  claim 12 , further comprising a stress release groove extending at least partially around the stud at a position between the middle portion and the second end. 
     
     
         19 . The reciprocating pump assembly of  claim 12 , wherein the stay rod assembly experiences cycling stresses having a maximum stress, a minimum stress, and a difference between the maximum stress and the minimum stress, wherein the difference between the maximum stress and the minimum stress is less than about 20% of the maximum stress. 
     
     
         20 . A method for assembling a reciprocating pump assembly, the pump assembly having a power section and a cylinder section, the power section reciprocatingly positioning a plunger toward and away from the cylinder section, the method comprising:
 securing a first end of a stud to the power section of the reciprocating pump, wherein the stud includes a middle portion extending between the first end and a second end and a shoulder positioned between the first end and the middle portion;   inserting a sleeve over the stud and pressing a first loading end of a sleeve against the power section such that the sleeve surrounds the middle portion of the stud and the first loading end is adjacent the shoulder of the stud;   inserting the second end of the stud through a flange of the cylinder section of the reciprocating pump assembly such that the second loading end of the sleeve abuts the flange of the cylinder section; and   securing a fastener onto the second end of the stud such that the fastener compresses the flange and the sleeve by a predetermined distance.   
     
     
         21 . The method of  claim 20 , wherein the predetermined distance is between about 0.02 inches to about 0.05 inches. 
     
     
         22 . The method of  claim 20 , wherein the first end and the second end of the stud comprises threads for respectively fastening to the power section and the fastener. 
     
     
         23 . The method of  claim 20 , wherein the stud further comprises a first stress release groove extending at least partially around the stud and located between the first end and the shoulder, and a second stress release groove extending at least partially around the stud and located between the middle portion and the second end, wherein the first stress release groove and the second stress release groove each includes a corresponding gradually varying rounding radius. 
     
     
         24 . The method of  claim 20 , wherein the stud and the sleeve experience cycling stresses having a maximum stress, a minimum stress, and a difference between the maximum stress and the minimum stress, and the difference between the maximum stress and the minimum stress is less than about 20% of the maximum stress.