NATE Member Advisory Bulletin – Wire Mesh Grip Safety Advisory
NATE Member Advisory Bulletin
Wire Mesh Grip Safety Advisory
At the request of members in response to a recent safety bulletin, NATE has engaged a Hoisting Grip Task Team comprised of Subject Matter Experts (SMEs) from contractors, owners, carriers, and manufacturers, to examine the use of Wire Mesh Grips, commonly referred to as “Hoisting Grips” within the telecommunications industry.
Thus far, these SME’s have been unable to locate a specific consensus standard, utilized by manufacturers, on the design, application, or use of wire mesh (hoist) grips for overhead lifting and/or supporting/securing cables to antenna supporting structures.
Until industry stakeholders can conduct further review/research of cable/line systems installations, this Task Team of SME’s suggests considering the following when working with wire mesh grips:
IS THE WIRE MESH GRIP:
· Compatible with cable/line being hoisted (i.e. feedline, transmission line, coax, hybrid, waveguide or approved by the Engineer of Record (EOR))?
· Equipped with a True Tag/Label identifying the manufacturer?
· Supplied with the manufacturer’s Instructions on use and installation instructions warnings?
· Approved or manufactured for lifting loads overhead – vertical lifts?
· Approved, manufactured and compatible for supporting, lifting, and securing the specific cable?
· Secured/attached to the structure per the Structure Owner/Manufacturer/or EOR Installation Guidelines?
KNOW YOUR LOAD: (for attachment, lifting, and securing cables using wire mesh grips)
· Do you have the information needed to complete a thorough rigging plan that includes the wire mesh grips?
· What is the grip’s rated capacity working load limit (WLL) or breaking strength with a safety factor of 5:1? Ex. Breaking Strength equals 3000 lbs., safety factor of five, would be a WLL for 600 lbs.
· Does the rated capacity maintain the recommended spacing of the wire mesh grip as provided to you by the cable manufacturer? Per the manufacturer, the grip spacing may be more frequent than the grip breaking strength implies, for the type of cable being hoisted due to potential crushing or damage to the cable and/or jacket.
· What is the weight of the cable/line – pounds per foot?
· How many grips are required for the cable/line being lifted?
· Can you Maintain Tension on the Wire Mesh Grip as per manufacturer requirements?
· Are the attachment points on the structure along with the components being used:
· Capable of supporting the wire mesh grip and the weight of the cable?
· Evaluated by a competent person, who has the support of a qualified person, that can engage a qualified engineer if necessary.
· Within the structure owners’ guidelines?
FOLLOW THE INDUSTRY STANDARD:
· Per ANSI/ASSP A10.48 10.5.2 Rigging Hardware and Slings, a minimum safety factor of 5:1 should be maintained to account for dynamic loads during lifting, or as specified by the Engineer of Record.
“Standard rigging hardware and slings used for lifting and load handling purposes shall be specifically certified for such applications in accordance with applicable ASME B30 standards. The use of rigging hardware not specifically covered by ASME B30 standards is discouraged but may be used if certified for lifting and load handling purposes by the component manufacturer or qualified engineer for the intended use and shall utilize a safety factor no less than 5.0.”
FOR SPECIFIC DIRECTIONS OR GUIDANCE, IT IS RECOMMENDED THAT YOU CONTACT YOUR CABLE OR GRIP MANUFACTURER
