barhale construction plc excavator pole grab standard · the above pictures (left) shows an...

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Barhale Construction plc

Excavator Pole Grab

Standard

(Specialist equipment)

This Standard to be read in conjunction with the requirements set-out in the Procedure for Safe Use of Pole Grabs on Site CPR510


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Appendix 1. Maintenance Check

1.1 Pre Hire – Check Sheet 2. Safety Features

2.1 Grab Extension Retaining Bolts - Extension Bolts – Extension to Top Swivel or Knuckle Bolts

2.2 Nordloc washers 2.3 Incorrect bolts and nuts 2.4 Safety chains 3. Risk Management 3.1 Generic excavator pole grab task risk assessment (CG4126) 3.2 Liebherr 934 Shaft sinking excavator task risk assessment (CG4127) 3.3 Three hourly pole grab inspection sheet (CF2290) 4. Best Practice 4.1 BCS hire pole grab 5. Safety Alerts 5.1 Historical grab related safety alerts 5.2 Bad practice


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1. Maintenance 1.1 Pre Hire Check Sheet All excavator pole grabs that are delivered to site from any supplier must have the last Pre Hire service check sheet (CF2306) with them. This is a mandatory requirement and will also demonstrate to the site management team that the pole grab has been through a Pre Hire quality check before being delivered to site. Example of a pole grab Pre Hire service sheet


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2. Safety features 2.1 Grab Extension Retaining Bolts - Extension Bolts – Extension to Top Swivel or Knuckle Bolts All grab retaining bolts, extension bolts and extension to swivel or knuckle joint bolts must be of a 10.9 tensile strength. They must also be by type black engineering bolts and not either zinc plated, nickel plated or galvanised. If there are any captivated studs in the grab assembly they must also conform to the 10.9 tensile strength standard. All tightening nuts used in conjunction with either the conforming bolts or studs must be black engineering nuts with a 10 grading. All bolts and tightening nuts must tightened to there correct specific torque setting. No set pins are to be used in the make of the grabs extenentions

Examples below

Black engineering bolt also showing a black engineering nut

The correct tensile/grade marking is shown clearly on the head of the bolts

Black engineering nuts showing the correct marking grade H 10


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2.2 Nord-loc Washers All black engineering bolts, nuts and captivated studs must have nordloc washers fitted as an anti realising mechanism. Information and identification picture below The NORD-LOCK bolt securing system uses geometry to safely lock bolted joints in the most critical applications. This unique wedge-locking system offers the following advantages:

• Maximum safety

• Resists loosening caused by vibration and dynamic loads

• Ease of assembly and disassembly

• Locking function is not affected by lubrication

• Positive locking at low and high preload levels

• Controllable preload

• Same temperature characteristics as standard bolt/nut


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2.3 Incorrect bolts and nuts Illustrations below show the incorrect bolts and nuts that must not be used on any excavator pole grab

Mild steel nyloc nuts

Mild steel nuts

Zinc/nickel plated bolts

Galvanized bolts

Set pins (fully threaded)


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2.4 Safety chains. All bolted flanges and joints must have a fail to safe safety chain fitted as shown below.

Picture showing an extension to extension coupling with welded eyes and fail to safe chains on both sides of the extensions

Picture showing top extension to rotating swivel with welded eyes and fail to safe chains on both sides of the extension and the rotating swivel

Picture showing bottom extension to clamshell grab assembly with welded eyes and fail to safe chains on both sides of the extension and clamshell gram assembly


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Picture showing the thickness of the flanges and gusset strengtheners on the extensions which help to keep the flange from distorting and also adding additional strength

3. Risk management

3.1 Generic Pole Grab Risk Assessment (CG4126) There is a generic pole grab risk assessment (CG4126) on Envoy which provides Site Management with mandatory controls to be implemented when grab attachments are fitted to excavators. The risk assessment cross-references this standard to ensure site personnel can identify best practice requirements. It is a mandatory requirement for Site Managers to implement the controls indicated in the risk assessment and ensure all assessments downloaded from Envoy are made site specific with residual risks scored accordingly. 3.2 Risk Assessment for Liebherr Grab Machines (CG4127) There is a specific task related risk assessment (CG4127) for the Liebherr 934 shaft sinking excavator available for use on Envoy. As for the generic pole grab risk assessment (CG4126) the control measures are mandatory requirements and are cross-referenced to this standard. The reason for the separate risk assessment from that of the generic risk assessment is that the Liebherr 934 machine is specifically dedicated to grab excavation work and requires additional risks to be assessed as a consequence. It is a mandatory requirement for Site Managers to implement the controls indicated in the risk assessment and ensure all assessments downloaded from Envoy are made site specific with residual risks scored accordingly. 3.3 Mandatory Daily Pole Grab Check Form (CF2290) It is a mandatory require for all site operations when grab excavation is being undertaken, that the grab retaining bolts, extension bolts and extension to swivel or knuckle joint bolts are physically checked for tightness by the machine operator every 3 hours. This is not just a visual check! CF2290 has been designed to ensure 3 daily checks can be undertaken by the Operator. Any defects found by the Operator must be recorded on CF2290 and reported to the Site Management and BCS Hire immediately to allow a Service Engineer to attend site and rectify the fault. The Service Engineer will confirm actions taken and record the details on the form CF2290. Completed weekly forms should be retained by the Site Team during the duration of the project for reference


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purposes. No work activities are to proceed in the event that a defect has been found on site until rectification and authorisation to proceed from both BCS Hire and the Site Management.

4.0 Best practise 4.1 BCS Hire excavator pole grab

The picture above shows an excavator pole grab in full with all its safety features


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5. Safety Alerts 5.1 Past grab related safety alerts Below are some historic internal safety alerts communicated within Barhale.


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5.2 Examples of Bad Practice

The above pictures (left) shows an excavator pole grab which is attached to the excavator’s quick hitch by a single mounting pin. This method of attachment is both un-safe and permanently banned from being used on any Barhale sites. The above picture (right) shows the correct quick hitch saddle configuration that must be used to connect the pole grab to the excavator.

The picture above shows an excavator pole grab that failed on a bolted joint. The main contributory causes why this happened were that the incorrect type of bolts was used in conjunction with the wrong type of tightening nuts. Also, the two mating flanges were found to be distorted allowing the joint to flex and exerted more forces on the retaining bolts. The joint also had no gussets to offer any additional strengthen to the joint.

barhale construction plc excavator pole grab standard · the above pictures (left) shows an...

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