GEARENCH U4174 PETOL HYDRA-TORK - Manual (Page 8)

8
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 can be caused by pulling or pushing on the tong in a direction that is not along a
perpendicular plane, unleveled mounting of the tong or 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 diameter 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 temperatures 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 apertures), wear and scoring
are not readily noticeable.