Wenzel Downhole Tools Ltd

Wenzel Downhole Hydraulic Fishing Jar (HFJ)

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The Wenzel Hydraulic Fishing Jar (HFJ) is extensively used for fishing, coring, testing, reaming, washover operations, etc., where the utmost in dependability is demanded. The HFJ was designed to provide maximum bore diameter without sacrificing performance, strength, and dependability. The HFJ works on a straight pull basis. Because it is hydraulic - hole deviation, hole drag, etc. will not stop the jar from firing as long as the jar realizes an upward force of any magnitude.

The Wenzel Fishing Jar is made primarily of AISI4145 Chromium-Molybdenum Alloy Steel which is heat treated and stress relieved. This composition results in tensile strengths exceeding 140,000 psi and Brinell Hardness ranging from 290-310. Some parts of the Wenzel Fishing Jar experience higher stresses and are made from Astralloy. This is a super-high strength alloy steel exhibiting tensile strengths of 170,000 psi. The metering valve is made from Aluminum Bronze, which has excellent wear characteristics and is machined to a tolerance of 0.0005". All body joints are made with 4 thread modified acme. This thread is used to eliminate stress concentrations which decrease the likelihood of cracks forming at the thread roots. Seals used are 90 durometer Buna N (nitrile) "O" Rings and Parbacks which have a working temperature range of up to 250oF (120oC).  These are superior to most elastomer type seals due to their high resistance to tear and abrasion. Special Fluorocarbon (Viton) seals are used for "hot hole" conditions of up to 450oF (230oC). Synthetic oil is used as the hydraulic fluid because of its ability to maintain stable viscosity through a wide range of temperatures. All these features are inherent in the design in order to ensure dependability and ultimate performance of the jar.

Benefits and Features

  • Jarring mechanism not subjected to torsional stresses
  • Metering valve can be reset rapidly with minimal weight
  • Metering valve provides for uniform hydraulic bypass thus eliminating frictional heat problems
  • A 4 - 6" free stroke (depending on size) is provided for maximum jar
  • All sealing areas have a total clearance of .003 - .005 between the 'bore' and  'rod' diameters
  • Internal and external hard chrome areas are held to tolerances of +/-.0005"

For more information and technical specifications please download the information sheet above.


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