0027/nd guidelines for Marine Lifting and Lowering Operations

MARINE
 
LIFTING
 
&
 
LOWERING
 
OPERATIONS 
0027/ND Rev 11 
 
Page 48 of 84 
14 
FABRICATION OF RIGGING AND LIFTING EQUIPMENT 
14.1 
INTRODUCTION 
14.1.1 
The following section covers the fabrication of slings, grommets, shackles and other lifting equipment.
The details contained in the following sections should be considered the minimum requirements as it 
may be that national standards, local standards or operator/contractor requirements may be more 
onerous.
14.2 
MATERIALS AND CONSTRUCTION OF STEEL SLINGS AND GROMMETS 
14.2.1 
The construction of steel slings and grommets should be according to a recognised code and method 
e.g. grommets are constructed and used in accordance with IMCA guidance, Ref. [7]. 
14.2.2 
Steel slings or grommets may be constructed from a single wire rope, or for cable laid slings or 
grommets, constructed from multiple wire ropes. 
14.2.3 
The quality and performance characteristics of all materials used in slings and grommets shall be 
adequate and documented. 
14.2.4 
The minimum breaking load (MBL) of steel wire-rope slings and grommets shall be documented (and 
certified) in accordance with a recognised standard. Documentation should clearly indicate how the 
stated MBL has been determined.
14.2.5 
Ideally, the MBL for wire rope should be determined by pulling a complete rope to destruction. Where 
adequate facilities are not available for such testing, the wire rope MBL should be established in 
accordance with a recognised standard.
14.2.6 
When fabricating steel slings or grommets from several individual ropes, the total MBL should normally 
be taken as the sum of the unit rope MBLs, divided by a sling spinning loss factor of 1.18. For 
grommets, the strength of the core element should not be included when calculating the MBL. 
14.2.7 
The sling eye length for cable laid slings should be no shorter than specified by the manufacturer or 
less than 10 times the rope diameter. The eye length should also suit the intended lift point detail 
(hook prong, shackle bow, etc.) and normally ensure that the internal opening angle of the sling does 
not exceed 20°. Where a sling eye internal opening angle exceeds 20°, it must be documented that 
the sling is still suitable for the intended use, allowing for any reduction in the capacity of the sling. The 
documentation supplied should include calculations and confirmation from the sling supplier of any 
reduction in the capacity of the sling. 
14.2.8 
Lengths and tolerances of steel slings and grommets should be adequately specified in order to fulfil 
the assumptions for the applied skew load SKL, see Section 5.6. 
14.2.9 
The length of steel slings and grommets should be documented by adequate measurements. During 
measuring, slings or grommets should be fully supported and adequately tensioned. The test tension 
should be agreed with the manufacturer and normally be in the range of 2.5% to 5.0% of the MBL.
Matching slings should be measured with the same tensile load and under similar conditions. The 
tension and the bending diameter during the tensioning test should be specified on the test certificate.
14.2.10 
If needed, the lengths should be measured at adequate tensions to establish the Elastic Modulus (E) if 
required in the determination of the skew load factor, see Sections 5.6.8 to 5.6.13. 
14.2.11 
Slings with hand spliced terminations must be prevented from rotation when the slings are loaded. 
14.2.12 
Steel slings or grommets required to be wet stored for an extended period prior to use (e.g. for the 
recovery of a subsea asset) shall have adequate resistance against all possible mechanisms of 
degradation and the material properties shall be documented accordingly. For certification 
requirements, see Section 15.2.4.