GEARENCH U118-000-G PETOL HYDRA-TORK - Manual (Page 9)

9
Tong and Vise Chain Inspection
The service life of leaf chains can be altered by a variety of adverse operating conditions.
The following information discusses the most important of these conditions for consideration
when operating or scheduling replacement of leaf chain systems.
Overloading / Shock Loads / Side Loading
Attempting to "inch loads which are beyond the rated capacity of the tool.
Striking the tool with a hammer or other object while force is being exerted in an attempt to
loosen a "frozen" joint.
Side pull on the chain. Side pull can be caused by pulling or pushing on the tong in a
direction that is not along a perpendicular plane, unlevel mounting of the vise, inadequate
support of the part being broken out, and improper seating of the part being broken out in the
tong or vise. Improper seating will occur when the O.D. of the part is not consistent within
the width of the tong or vise jaw.
Environmental Conditions
Wrench chains operate in widely varying environments, from wet outdoor conditions to
mildly or highly corrosive industrial atmospheres. They can also be exposed to abrasives
such as sand or grit.
The possible effects include:
Moisture - Corrosion and rust reduce chain strength by causing pitting and cracking.
Temperature - Very cold temeratures reduce chain strength by embrittlement.
Chemical Solutions or Vapors - Corrosive attack of the chain components' grain
structure and/or the mechanical connections between the chain components (crevice
corrosion) may occur. Cracking often is microscopic. Propagation to complete
failure can be eventual or sudden.
Abrasives - Accelerated wearing and scoring of the articulating chain members (pins
and plates) may occur, with a corresponding reduction in chain strength. Due to
inaccessibility of the bearing surfaces (pin surfaces and plate aperatures), wear and
scoring are not readily noticeable.