What Is a Valve Tag?

Quick Answer

A valve tag is a unique alphanumeric identifier assigned to each valve in a piping system for tracking, maintenance, and operational purposes. The tag number appears on P&IDs, isometric drawings, valve data sheets, and a physical metal tag attached to the valve in the field. Valve tagging enables operators to locate, operate, and maintain any valve in a plant by referencing its unique number across all project documentation.

Valve Tag Format

Valve tag numbering systems vary by company and project, but most follow a structured format that encodes the valve’s location, type, and sequence number. A typical tag format:

[Area]-[Valve Type Code]-[Sequential Number]

Example: 10-HV-0105 means Area 10, Hand Valve, sequence number 0105.

Common valve type codes used in tag numbers:

Code	Valve Type	Example Tag
HV	Hand valve (manual, generic)	10-HV-0101
XV	On/off valve (actuated)	20-XV-0205
FV	Flow control valve	10-FV-0301
PV	Pressure control valve	30-PV-0401
TV	Temperature control valve	10-TV-0501
LV	Level control valve	20-LV-0601
PSV	Pressure safety valve	10-PSV-0701
BDV	Blowdown valve	30-BDV-0801
SDV	Shutdown valve	20-SDV-0901
NRV	Non-return (check) valve	10-NRV-1001

What Information the Valve Tag Carries

The physical valve tag (typically a stamped stainless steel plate wired or chained to the valve) shows the tag number. However, the tag number links to a comprehensive valve data sheet that contains all technical details:

Valve Data Sheet Field	Description
Tag number	Unique identifier (e.g., 10-HV-0105)
P&ID reference	Drawing number where the valve appears
Line number	Piping line the valve is installed in
Service	Fluid and process conditions
Valve type	Gate, globe, ball, butterfly, check, etc.
Size	NPS / DN
Pressure class	ASME class or PN rating
Body material	ASTM grade (e.g., A216 WCB)
Trim material	Seat, stem, disc material
End connection	Flanged, butt-weld, threaded
Actuator type	Manual, pneumatic, electric, hydraulic
Fail position	Fail-open, fail-close, fail-last (actuated valves)

Valve Tag Register

The valve tag register (or valve list) is a master spreadsheet that compiles all valve tags for the project with their key attributes. It is maintained by the piping or instrumentation engineering team and is used for:

• Material requisition and procurement
• Vendor bid evaluation
• Factory acceptance testing (FAT) scheduling
• Installation tracking during construction
• Commissioning and handover to operations

The valve register links directly to the P&ID symbols and instrument data sheets.

Common Mistake

Reusing valve tag numbers from decommissioned or removed valves creates confusion in the maintenance management system (CMMS). Historical maintenance records, inspection reports, and incident logs reference the original tag. If a new valve receives the same tag, its history merges with the old valve’s records, corrupting the data. Always assign new, unique sequential numbers to replacement valves and cross-reference the superseded tag in the register.

Valve tags are part of the broader equipment identification and tagging system used throughout EPC project execution.

Read the full guide to piping engineering