SAFETY ALERT AT OIL RIG PLATFORMS: Misuse of Beam Clamps as Ground THAT CAN
CAUSE FIRES AND OTHER ELECTRIC HAZARDS
The Bureau of Safety and Environmental Enforcement (BSEE) has
identified a potential safety issue in regard to the use of beam clamps on many
Outer Continental Shelf (OCS) facilities. It is determined that the use of beam clamps
as grounding conductors could potentially cause fires and present electrical hazards to personnel.
Many OCS facilities are utilizing beam clamps as current
carrying external ground to meet the requirements in the API RP 14F. The beam clamps are approved by Underwriters
Laboratories (UL) and FactoryMutual Research Corporation (FM) to mount and
support conduit and cable from structural beams, not as temporary or permanent
external equipment grounding conductors. Examples of beam clamps are shown below:
API RP 14F & 14FZ § 6.10.3.1 states: “Grounding of
electrical equipment on fixed and floating offshore petroleum facilities in a
positive manner is of particular importance because personnel standing on steel
decks or in contact with steel framing present a low impedance path to ground,
effectively grounded. In addition, the dampness and salt spray contribute to
the breakdown of insulation and to the possibility of leakage on the surface of
insulators and similar devices. On platforms with wooden or concrete decks,
equipment-grounding conductors should be installed between electrical equipment
and a grounding network.
It is recommended that all metal equipment, such as buildings,
skids, and vessels be grounded to the steel structure or grounding network.
Exposed, noncurrent-carrying metal parts of fixed equipment that may become
energized because of any condition shall be grounded. Equipment that is welded
to the structure or deck is considered to be adequately grounded. The physical
contact obtained when equipment is bolted to a steel structure is not
necessarily an adequate effective ground because of paint and possible
corrosion. Exposed, noncurrent-carrying metal parts of portable electrical
equipment shall be grounded through a conductor in the supply cable to the
grounding pole in the receptacle.”
These grounding jumpers
do not meet the requirements in API RP 14F/API RP 14FZ.
API RP 14F & 14FZ both make a clear requirement that any
equipment that has exposed, noncurrent-carrying metal parts that may become
energized because of any condition shall be grounded. In this requirement, it
is clear that during a fault condition this grounding means must be capable of
reliably conducting the ground fault current back to the source of electrical
power to activate or trip the electrical circuit protective device. To further
clarify, if the equipment is not electrically powered and the metal parts
associated with that equipment become energized due to no association with
electrically operated equipment, controls, devices, or lighting, then the
requirement for approved current carrying conductors, lugs, terminals, etc.
should not apply.
Operators, as well as contractors, are advised to review your
facilities in comparison with these best practices and guidelines.