WAZIPOINT Engineering Science & Technology: Plant Safety and Security Guides

Thursday, November 9, 2023

Plant Safety and Security Guides

Safe and Secured Plant Access for Operation and Maintenance in Hazardous Area Provide Guard and Lock System

Safe and Secure Plant Access for Operations and Maintenance in Hazardous Areas: Guard and Lock System

The plant and equipment provided in accordance with this specification, shall either by its design and/or selection, or by additional sound-absorbing enclosures supplied as part of this contract, meet the noise level requirements for both general work area limits and neighborhood noise limits as specified herein.

The plant and equipment shall be deemed to meet the requirements of this specification if the noise levels measured, or calculated from measurements after background and other corrections have been applied, and after any appropriate tolerances have been allowed in accordance with the given standards do not exceed the noise limits specified.

The nomenclature, measurement, and calculation procedures and the procedure for acceptance shall be in accordance with the Oil Companies Materials Association (OCMA) Noise Procedure Specification, NWGI. Measurements shall be made of the ‘A’ weighted sound levels, dB (A), and also of the unweighted octave band sound pressure levels, dB, at the nine centre frequencies of 31.5 Hz to 8 kHz.

In accordance with recommendations made in the OCMA specification the sound levels measured at the specified locations for neighborhood noise limits shall be compared with the BS 4142. ‘Method of Rating industrial Noise Affecting Mixed Residential and Industrial Areas’ to determine whether any adjustment is required.

The sound level after used for the tests shall be of the precision type and comply with the British Standards BS 5969 or the International Electro technical Commission Standard, IEC 651, Type 0. The octave band pass filter set shall comply with BS 2475 or IEC 225. The slow meter response setting shall be used.

Should the tests show that the noise levels exceed those specified the Service-provider shall at his own expense make such changes of the plant and equipment or provide additional sound attenuation equipment as may be necessary to meet the specified levels, to the approval of the Engineer.

Hazardous Areas Working Procedure in a Safe Way

The Service-provider shall take full account of any special requirements concerning the nature, handling, and storage of all fuel oils, gases chemicals, etc., and provide plant, equipment, buildings, and other services accordingly including all facilities to ensure the safety of the operating and maintenance personnel.

The service provider shall provide drawings to define all the hazardous zones taking account of all sources of hazards under normal and abnormal operating conditions, regardless of whether or not these areas are specifically listed in the specification. The zoning philosophy shall be in accordance with the National Electric Code and will be subject to the approval of the Engineer.

In particular equipment directly concerned with the plant which may give rise to a hazardous situation shall be designed to IEC 79 Zone 1 or 2 requirements with electrical connection safety barriers or intrinsically safe equipment equivalent to VDE 0171 Type Exit. Where required by the Engineer, certification shall be provided to confirm the suitability of the equipment and devices.

Electrical equipment shall not be installed in Zone 0 areas without the approval of the Engineer, though this does not preclude cables from passing through such areas.

The service provider shall be responsible for ensuring that all electrical equipment installed in any hazardous zone is designed and tested to suit the relevant zone classification and shall be to the approval of the Engineer.

Access for Operation and Maintenance

The service provider shall supply and erect all platform galleries, stairways, accessways, and ladders necessary for providing safe and easy access to the plant items for operation and maintenance. The service provider shall ensure that the whole of the access ways are of uniform design and pattern throughout the Works.

How do Interlocks Work?

Can you explain the working mechanism of interlocks? Additionally, please correct any errors related to spelling, grammar, or punctuation.

A complete system of interlocks and safety devices shall be provided so that the following requirements and any other conditions necessary for the safe and continuous operation of the plant are provided:

Safety of personnel engaged in operational and maintenance work on the plant.
The correct sequence of operation of the plant during starting up and shutting down periods.

To ensure a safe plant while operating under normal or emergency conditions.

Interlocks shall be preventive, as distinct from corrective in operation.

Where a plant supplied under this Contract forms the whole or a part of a system for which one or more interlocking schemes are required, the Service Provider shall be responsible for all interlocking schemes for the Engineer’s approval. General descriptions of interlocking requirements are given in the Specifications but the Service-provider shall include any other interlocks he considers necessary.

Guards on Moving Parts

All moving parts; shafts, couplings, flywheels, bare conductors and hot or cold surfaces shall be adequately and securely guarded in accordance with the proscribed legislation and to the Engineer's approval so as to afford complete safety to all personnel.

Locks, Padlocks, and Key Cabinets

The Service-provider shall provide padlocks, locks, chains or other locking devices for the locking of all equipment cubicles, electrical isolating switches, selector switches, valves, etc. to the approval of the Engineer.

All locking devices and chains shall be manufactured from corrosion-resistant material. All mechanisms shall be provided with a cover to minimize the entry of water or dust.
Locks shall conform to a master keying feature system to be agreed upon with the Engineer for groups of equipment.

All locks shall have individual high integrity locks and shall be provided with (two) keys.

Each key shall be provided with a label as specified.

The service provider will supply and fit key cabinets equipped with labeled hooks, each Identified with its appropriate key. Every cabinet shall be provided with a nameplate identifying the cabinet with its respective item or items of plant. Sufficient cabinets will be provided to store all keys supplied under this Contract and cater for future extensions.

The service provider shall provide comprehensive lock and key schedules to readily permit identification with equipment and doors. Such schedules are not required for loose padlocks.

Where modifications are performed to existing sites the Service-provider shall provide a system identical to that existing.


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