ST 80

ST80-04-02
Rev A
Page 1 of 3
Date: December 15, 2004
Subject: Detachment of Duplex Extension Cylinder/Clevis on ST-80
Product: All ST-80 Iron Roughnecks
Affected
Assemblies: ST-80 Platform Assembly (P/Ns 30160030 and 30171698)
Note: Inspect your serial number nameplate for the last three digits (e.g.
ST80A01K001). Affected units include serial number 001 up to and including 091 and
serial numbers 301 up to and including 382.
Objective: Advise Operators of Cylinder Upgrade to Prevent Possible Clevis Failure
Problem: The initial release of this product bulletin notified operators of an incident that occurred
when the clevis detached from the Duplex Extension Cylinder (P/N 30170579) while
the operator was extending the ST-80 Iron Roughneck to well center.
The ST-80 Carriage was approximately one foot from well center when the clevis
detached from the rod on the support arm end of the cylinder. As a result, the carriage
pivoted forward and came to rest against the drill pipe. No injuries were reported as a
result of this incident.
The investigation has determined that the cylinder manufacturer may not be installing
the rod end clevis on the duplex cylinder to the required torque. A clevis not torqued
properly can result in a fatigue failure of the clevis threads and detachment of the
clevis from the cylinder rod.
Solution: As a precautionary measure Varco has established a plan to provide hardware to
upgrade all ST-80 Duplex Extension Cylinders. The upgrade will consist of replacing
the two existing clevises with new ones and torquing both to 500 ft-lbs.
The Extension Cylinder Upgrade Kit (P/N 30175331) includes two new clevises, a
greasable pivot pin and bushings, a special wrench and a kit drawing providing
detailed instructions to the rig for implementing this upgrade.
Product Bulletin No.: ST80-04-02
Revision A
Release ST-80 Iron Roughneck

ST80-04-02
Rev A
Page 2 of 3
To upgrade these duplex cylinders Varco will supply the kit parts only, free of charge.
Each ST-80 owner should provide a no cost purchase order to your local Varco
Service Center to order the kit.
Varco recommends that all ST-80 operators immediately inspect the Duplex Extension
Cylinder for loose or damaged clevises. Extension of the ST-80 will be required to
verify that no gap exists between the rod end clevises and the rod ends. See Figures 1
& 2.
If any damage or gap between the clevises and rod end is observed discontinue use
until the kit is received and installed. Please contact your local Varco Service Center if
you have any questions regarding this product bulletin.
Figure 1
ST-80 Iron Roughneck
Pedestal
Column
Support
Arm
Carriage
Assembly
Extension Duplex Cylinder

ST80-04-02
Rev A
Page 3 of 3
Figure 2
Close up View of Duplex Extension Cylinder (Support Arm End)
Support
Arm
Cylinder
Clevis
Cylinder
Rod
Note: Inspect for
gap between
clevis and rod
end shoulder

ST80 Index
No. Safety
Alert
Rev Title Date
Rel. Effectivity
ST80-03-01 - - ST-80 Performance Issues
1/29/03 All H & P ST-80 Iron Roughnecks
ST80-03-02 Yes B ST-80 Control Valve Assembly Damaged
Resulting in Pinch Hazard
7/7/03 All ST-80 Iron Roughneck
ST80-03-03 - - ST-80 Handling Instructions for Lifting and
Transport
6/13/03 All ST-80 Iron Roughneck
ST80-03-04 - - ST-80 Operating Instructions for
Positioning 6/13/-03 All ST-80 Iron Roughneck
ST80-03-05 - - ST-80 Instructions for Proper Use of
Spinning Wrench Controls
6/13/-03 All ST-80 Iron Roughneck
ST80-03-06 - - ST-80 Set-up Instructions for System
Pressure Setting
6/13/-03 All ST-80 Iron Roughneck
ST80-03-07 - - ST-80 Hose Abrasion 7/7/03 All ST-80 Iron Roughneck
ST80-04-01 - - Revisions to Lubrication Frequency on
ST-80
5/10/04 ST-80 Wrench
ST80-04-02 Yes A Detachment of Duplex Extension
Cylinder/Clevis on ST-80 12/15/04 ST-80 Platform Assembly (P/Ns 30160030 and
30171698)
Affected units include serial
number 001 up to and
including 091 and serial
numbers 301 up to and
including 382.