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2.2 - Preparation of Tinned or Plated Surfaces of Bolted Joints

EHV Structures Ltd - Work.Instruction_01

Purpose

This work instruction outlines the proper procedure for preparing tinned or plated surfaces of bolted joints to ensure optimal electrical contact and joint reliability.

Scope

This instruction applies to all maintenance and installation procedures involving electrical bolted joints with tinned or plated surfaces.

Equipment and Materials Required

Elecsol 41 or Elecsol Super solvent

Clean lint-free cloths

Toothbrush or nylon nailbrush

Grade 400 oxide paper (for nickel plating)

Castrol Rustilo 431 grease or equivalent

Petroleum jelly (for joints in transformer oil)

Appropriate PPE (gloves, eye protection)

Deburring tools

Safety Precautions

Always wear appropriate PPE when handling solvents

Ensure adequate ventilation when using cleaning solvents

Follow all relevant safety procedures for electrical equipment

Procedure

1. Surface Cleaning

1.1. Inspect the surfaces for dirt, grease, or other contaminants.

1.2. Apply a suitable solvent (Elecsol 41 or Elecsol Super) to a clean cloth.

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1.3. Wipe the surfaces thoroughly to remove all dirt and grease.

1.4. Ensure surfaces are completely dry before proceeding.

2. Burr Removal and Surface Inspection

2.1. Carefully inspect all bolt-holes and edges for burrs.

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2.2. Remove any burrs found around bolt-holes or edges.

2.3. Check for flatness - busbar or strip should be completely flat.

2.4. Correct any bowing or distortion in the surface.

3. Plated Surface Preparation

3.1. Assess the condition of plated surfaces:

CAUTION: Do not prepare plated surfaces unless they appear badly tarnished.

3.2. For tarnished plated surfaces:

Use a toothbrush or nylon nailbrush to gently remove tarnish

Ensure cleaning is done without scratching the plating

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3.3. For nickel plated surfaces:

Note: Nickel plating has a surface film which can inhibit good contact if the contact pressure is low

If necessary, lightly abrade this surface with grade 400 oxide paper

Abrade tightly and carefully to avoid excessive removal of material

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4. Surface Coating Application

4.1. Without delay after preparation, coat each surface with a thin layer of approved grease.

IMPORTANT: Apply coating promptly to prevent re-oxidation of the prepared surfaces.

4.2. Apply Castrol Rustilo 431 or equivalent approved grease for jointing.

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4.3. Ensure an even, thin layer covers the entire contact surface.

5. Special Case: Transformer Oil Applications

5.1. For bolted joints that will be working in transformer oil:

Use Petroleum Jelly instead of other greases

NOTE: Other greases may be chemically incompatible with transformer oil.

Quality Control

Ensure all surfaces are clean and free from contaminants

Verify burrs have been completely removed

Confirm surfaces are flat with no distortion

Check that an appropriate thin layer of grease has been applied

Troubleshooting

Troubleshooting

Problem

Possible Cause

Solution

Poor electrical contact

Inadequate surface preparation

Repeat cleaning and preparation process

Visible oxidation after preparation

Delay in applying protective coating

Clean again and apply coating immediately

Residue on surfaces

Improper solvent cleaning

Use fresh solvent and clean thoroughly

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Document Revision History

Document Revision History

Revision

Date

Description of Changes

1.0

25/03/2025

Initial release

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