🔩 Piling & Drilling Rigs
Diaphragm Wall Grab Inspection & Certification in Saudi Arabia
A diaphragm wall grab is a heavy clamshell bucket, hung from a crane on ropes or on a kelly bar, that excavates deep slurry-supported trenches for diaphragm walls, deep basements and cut-and-cover tunnels. On Saudi metro, basement and port projects the grab works far below the crane, where visual checks are impossible. Its hydraulic closing cylinders, hose reel, verticality system and suspension must therefore be examined above ground, because a failure at depth is costly and dangerous to recover.
What we inspect on a diaphragm wall grab
- ✓Grab body, jaws and teeth for cracked welds, wear and deformation, including jaw pivot pins and bushings
- ✓Closing cylinders, cylinder pins and rod condition on hydraulic grabs
- ✓Hydraulic hose reel, supply hoses, swivel and quick couplings for abrasion and slurry damage
- ✓Suspension wire ropes, rope sockets, lifting yoke or kelly bar connection, with ropes assessed against ISO 4309 criteria
- ✓Verticality and depth sensors, cabling and the cab display, checked against a known reference angle
- ✓Guide frame and side guide plates for bending that would let the grab wander off line
- ✓Added weight plates and their fixings, and the total grab weight compared with the supporting crane's load chart
- ✓Hook block, shackles and connections between the crane and the grab
Common defects we find
- ✓Cracks at jaw hinges and in the weld between the grab body and the lifting yoke
- ✓Slurry-abraded hoses and leaking or seized hose reel swivel joints
- ✓Worn jaw pivot pins that loosen alignment and produce off-vertical panels
- ✓Faulty or uncalibrated inclination sensors giving false verticality readings
- ✓Wire rope broken wires and internal corrosion near the socket from slurry exposure
Risks of operating uncertified
- ✓A dropped or lost grab in the trench after a failed rope, socket or pin
- ✓Out-of-plumb panels that leak or fail to meet the structural wall design
- ✓Crane overload or overturning if the grab and attachment weights exceed the load chart
Testing, standards & frequency
Load / performance test
Not applicable: the grab is not given a rated-capacity lifting test as a standalone appliance. Instead the suspension and lifting points are inspected, the hydraulic closing and opening cycle is function- and pressure-tested, and the supporting crane is checked against its load chart for the total suspended weight.
Inspection interval
Typically before mobilisation to each wall package and at least annually, with re-inspection after heavy rock or obstruction work or where client or site rules require.
Standards referenced
- EN 16228 (Drilling and foundation equipment - Safety, including diaphragm walling equipment)
- ASME B30.5 (mobile and crawler cranes carrying the grab)
- ISO 4309 (wire rope care, inspection and discard)
- Manufacturer specifications and load charts
Part of our Heavy Equipment Testing & Inspection service. You receive an inspection report, Certificate of Conformity and inspection tag for passing equipment.
Industries using this equipment
FAQs
Can a diaphragm wall grab be inspected on site before it goes into the trench?＋
Yes. The grab is usually laid out or hung clear of the ground so the body, jaws, pins, hoses and ropes can be examined and the sensors checked against a known angle before it enters the slurry.
What affects the verticality accuracy of a diaphragm wall grab?＋
Worn jaw pins, a bent guide frame and faulty inclination sensors can all produce out-of-plumb panels. These items are checked during inspection alongside the ropes, hoses and cylinders.