1. Human Factors Engineering:
Valve Access and Design
Martin Robb CPE

2. Aims
• This note has been written to identify some issues associated with design and placement of
manual valves.
• The aim is to ensure that valves can be used safely by operations and maintenance personnel.
Common Valve Problems
Valves are a source of frequent human interaction with the plant and access may be required in
an emergency. It is important to ensure the design and arrangement of valves supports the
tasks. Some common issues include:
•Valves that require more torque to open than operators can produce (too difficult to “crack”);
•Valves that take too long to open or close due to large number of turns;
•Valves that must be operated from an awkward posture, leading to injury.
Some example access issues (from an onshore project) are shown in the figures below.
BlockedToo High Hard to access

3. General Valve Access Guidelines:
•Locate valves in spaces normally entered without tools;
•Ensure valve is not surrounded by obstructions, moving equipment, hot
surfaces etc. that could delay operation and maintenance;
•Ensure a safe standing surface is provided (avoid having operator stand on
pipes, trays etc. to access);
•Locate valves within arm’s reach.
General Valve Design & Layout Guidelines:
•Provide at least 75mm (3”) clearance between outside of valve handwheel /
lever and any obstacle;
•Ensure maximum force required to initially crack a valve does not exceed
450N (100 lb);
•Provide a position indicator; this should be visible from the valve operating
position;
•Use a mechanical extender rather than chain operator where necessary;
•Ensure handwheel or lever does not extend into normal walking areas.

4. Valve Criticality Analysis
•Categorize valves to determine access requirements;
•May be performed in a workshop setting (time‐consuming) or by setting
generic categories then managing by exception;
•Systematizes process and provides clear design criteria. Can avoid
unnecessary pipework / access platforms.
Category Use Description Access
1 Critical for safety or operations. Also used
frequently (at least once per 6‐month period) for
routine operation and maintenance
a) Deck level or via permanent elevated
surface.
b) Stair if above not practical.
2 Not critical but required for routine operation &
maintenance.
As above, but vertical ladder with purpose‐built
standing surface, mobile platform or scaffolding
may be used with written permission from
procuring agency.
3 Not critical; used infrequently e.g. during startup
or rarely‐performed maintenance tasks.
Permanent accessibility is desirable for these
valves but is not mandatory.
Indicate access requirements on drawings,
including clearance for personnel, tools, parts and
access equipment.

5. Design Checklist
The checklist below may be used with the Figures and Tables on the proceeding pages.

6. Source: ASTM‐F‐1166 (2007) Standard Practice for Human Engineering Design for
Marine Systems, Equipment and Facilities.