This article is about General Instrumentation Workspace Clearances in Plants and Refineries of Instrumentation and Control Systems as per International Codes and standards for Commercial Buildings, Plants and Refinery Projects.
General Instrumentation Workspace Clearances in Plants and Refineries
Material Receiving General Checklist for Instrumentation & Control
General Requirements
General: Plant facilities shall be provided with acceptable access and egress for personnel, materials, and equipment by using accessways, ladders, roads, stairways, stiles, and walking/working surfaces (decks, floors, grade, platforms, ramps, runways, and walkways) based on the requirements in this standard.
Access Requirements for Equipment Regularly Operated or Maintained or Operated in an Emergency: For equipment regularly operated or maintained or operated in an emergency, such as valve hand wheels, instrumentation, controls, and their associated manifolds, the distance, if located outside the handrails, from a fixed walking/working surface to the operating point shall be between 500 mm and 1500 mm vertically and a maximum of 510 mm horizontally. It shall be located away from top rail, midrails and supports to allow access.
“Access Requirements for Equipment Regularly Operated or Maintained or Operated in an Emergency: Access is also acceptable for instrumentation, controls, and associated manifolds
if the distance from the outside of a fixed ladder or fixed stairs to the operating point does not exceed 510 mm.”
“Access Requirements for Valves Not Regularly Operated:
Valves not regularly operated shall be accessed from portable platforms, portable stairs, portable ladders, or temporary scaffolding if access from fixed walking/working surfaces or fixed stairs is not provided.”
Access/Egress Clearances for Personnel: Minimum clear width of walking/surfaces, stairways and stiles shall be 760 mm.
Access/Egress Clearances for Personnel: The minimum clear width for tank stairways shall be per SAES-B-054 Section 7, Paragraph (6.3).
Access/Egress Clearances for Personnel: The minimum clear width shall be 910 mm where working area is needed such as in the front of a manhole for servicing trays, the end of a heat exchanger for servicing the bonnet, channel, and tube bundle, or around rotating equipment.
Access/Egress Clearances for Personnel: The minimum clear width of aisles shall be 1020 mm. (An aisle is personnel walking space around equipment at grade level.)
Access/Egress Clearances for Personnel: The minimum headroom above walking/working surfaces shall be 2030 mm, measured to the lowest point of an overhead obstacle.
Access/Egress Clearances for Personnel: The minimum vertical clearance under vertical furnaces shall be 2030 mm.
Access/Egress Clearances for Personnel: The vertical clearance above any stair tread to an overhead obstruction shall be at least 2030 mm measured from the leading edge of the tread.
“Personnel Ramps: Personnel ramps shall be designed per SAES-M-001 and SAES-M-100 and shall be constructed of steel per 12-SAMSS-007.
Exception: The slip resistant walking surface shall not be steel.
Flow Instrument Workspace Clearances
Field instruments (transmitters, indicators, I/Ps, etc.) shall be installed in an accessible location with centerline 1.4 m (nominal) above grade or platform and as close as possible to the flow element.
Level Instrument Workspace Clearances
Location and Orientation: Local instruments shall be accessible at grade level or from a platform.
Location and Orientation: Local level sight gauges and magnetic level indicators shall be accessible from grade level, platform or fixed ladder.
Location and Orientation: Standpipe and individual level instruments shall be connected directly to vessels and not to inlet or outlet piping.
Location and Orientation: Connections to the bottom of vessels shall be avoided whenever possible. However, when used, bottom vessel connections shall include an internal nozzle extension to reduce bottom solids from entering the standpipe.
Location and Orientation: Local receiving instruments shall be installed 1.40 m above grade level.
Access requirements shall meet SAES-B-054.
Temperature Instrument Workspace Clearances
All temperature instruments, connections, and primary elements shall be located to provide safe access for installation and maintenance.
Instrumentation requiring frequent access, such as local controllers, shall be located no more than 1.5 meters above grade or permanent platform.
Instruments requiring limited access, such as temperature transmitters, shall be no more than 3 meters above grade or permanent platform, and be accessible by ladder or mobile platform.
Combustible Gas and Hydrogen Sulfide in Air Detection Systems
Accessibility: Detectors shall be readily accessible for calibration. If necessary, access platforms shall be provided as needed, per SAES-B-054.
Analyzer Shelter Workspace Clearances
- Shelter Location: A minimum free access of 3 m shall be provided to all exterior building sides.
Exception: The intent is to provide adequate working space around analyzer shelters to facilitate routine maintenance (the movement of equipment in and out of the shelter, storage of gas cylinders, and working space for maintenance personnel) and to provide a clear path in the event of an emergency. A minimum of 1 m distance from the analyzer shelter to structural steel columns is acceptable provided free access to sample conditioning systems and exit doors is available.” - Shelter Size: Shelters interior shall be large enough to allow adequate access and space for maintenance work. If operational or maintenance access is required to any equipment enclosure, provide a minimum free space of 1 meter on the side that requires access.
- Shelter Size: All shelters greater than 10 square meters in size, shall have at least two exits, located at opposite ends of the shelter.
- Shelter Size: Shelters shall provide internal space for the addition of one equivalent analyzer (minimum) with room for additional associated sample systems on the outside wall of the shelter.
In addition to the basic construction requirements defined in 12-SAMSS-014 above, the shelter shall incorporate the following features: Doors shall open outwards and shall have steel frames. Doors shall be sized to permit the removal and installation of equipment. - In addition to the basic construction requirements defined in 12-SAMSS-014 above, the shelter shall incorporate the following features: An inspection window shall be installed in each shelter door (reference EN 61285, Section 7.4.4). Glass shall be laminated or tempered safety glass meeting the requirements of ANSI Z97.1. Glass thickness shall be at least 6 mm. The laminated
glass shall have a 1.5 mm interlayer.” - In addition to the basic construction requirements defined in 12-SAMSS-014 above, the shelter shall incorporate the following features: All doors shall be equipped with quick-opening bars (panic bars) on the inside, which shall override exterior locks.
Burner Management, Combustion and Waterside Control Systems for Watertube Boilers
- Access shall be allowed to facilitate testing, calibration and maintenance.
- The position of local indicating instruments shall enable them to be observed from grade, platform or walkway while related equipment is operated or when primary instruments are being tested or calibrated.
- Instruments and components shall be located so that they are protected against direct drainage or blowdown of condensate, water or process fluids from adjacent equipment.
- All locally mounted instrumentation and associated control equipment shall be accessible from grade, platform, or fixed walkway to facilitate testing and maintenance. Where necessary, provide standoff shielding around instrumentation to prevent operator contact with high temperature surfaces, as per requirements in SAES-F-001.
Process Heaters Safety Systems Workspace Clearances
- The process heater local control/shutdown panel shall be located so that the power operated fuel gas emergency isolation valves (EIV, also called a ZV) can be seen.
Control Valves Workspace Clearances
- Handwheels: A handwheel shall be provided on valves when local manual control is required by the Proponent. Handwheel installations shall meet the following requirements: Handwheel shall be fully accessible for operation.
- Control valves shall be installed such that they can be easily removed for maintenance including angle control valves
- Control valves and their actuating systems shall be mounted such that all adjustments are accessible (and all indicators/gauges are readable) from grade, permanent platform, walkway or fixed ladder.
Portable platforms and portable ladders shall not be used. - Sufficient clearances shall be provided for the removal of any part of the control valve or actuator assembly.
- Access space for lifting equipment shall be provided for valve and actuator assemblies weighing over 50 kg.
Control Buildings Workspace Clearances
- The main entrance to the control building, which shall face away from the process plant or face the plant considered to have the least risk of fire or explosion, shall be provided with an air lock to sustain building pressurization. Locks are not required for emergency exits and service entrances. Certain emergency exist doors may be restricted from being opened from outside, but personnel shall be able to open them from inside.
- The floor plan shall be designed to minimize casual personnel traffic through the control room. Offices and equipment rooms should be connected by internal corridors. For Central Control Buildings, the main entrance shall open onto a lobby or corridor from which the control room, offices and other facilities are accessed. For a Local Control Building, the main entrance may open directly through an air lock to the control room area.”
- The computer room (when specified), engineering room and process interface room (rack room) shall have their main access through the control room
- Emergency exits shall provide easy exit routes from each room and from the control building in accordance with SAES-M-100.”
- Double doors shall be installed to provide outside access to the control room, equipment rooms and rack rooms as required. If the control room is elevated above grade then loading platforms with stairways shall be provided to facilitate equipment handling during installation and maintenance. Equipment access doors shall be kept locked during normal operation and shall meet the blast resistance requirements of the structural walls of the building.
International Standard and Codes for Instrumentation Accessories
- Turbine Meter Material Selection Criteria Design & Flow Measurement
- Pitot Tube Design Requirement in Process Industry
- SAES-B-054 – Access, Egress, and Materials Handling for Plant Facilities.
- SAES-J-100 – Process Flow Metering.
- SAES-J-300 – Level.
- SAES-J-400 – Temperature.
- SAES-J-505 – Combustible Gas and Hydrogen Sulfide in Air Detection Systems.
- SAES-J-502 – Analyzer Shelters.
- SAES-J-602 – Burner Management, Combustion and Waterside Control Systems for Watertube Boilers.
- SAES-J-603 – Process Heaters Safety Systems.
- SAES-J-700 – Control Valves.
- SAES-J-801 – Control Buildings.
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