Piping system lockout procedures

Before work begins the employer must secure, blank, and then lock or tag the isolation/shutoff valves and open drain connections for visual observation of drainage. This is required by 1915.163(a).

• Secure and blank the valves that connect the dead (isolated) system to any live system(s).
• Apply a lock or tag in accordance with 1915.89 to show employees are working on the system and to prevent re-energizing or re-opening until it is safe.
• Open drain connections on all dead interconnecting systems so someone can visually confirm drainage, per 1915.163(a)(2).

These actions must remain in place until it is determined the system can be made live without creating a hazard or until the work is complete, as required in 1915.163(a)(1).

When valves are welded instead of bolted, the employer must secure at least two isolation and shutoff valves and then lock or tag them in accordance with 1915.163(a)(1).

• The rule explicitly requires "at least two" valves when welding replaces bolting to provide positive isolation.
• Locks or tags must meet the requirements in 1915.89.

This helps ensure redundancy so the dead system cannot be accidentally reconnected to a live system while employees are working.

Yes, an employer may use either locks or tags, but they must be applied in accordance with 1915.89 and only when they provide adequate protection. See 1915.163(a)(1).

• Tags are allowed by 1915.163(a)(1) but are generally considered to provide less positive physical restraint than locks. Employers should follow the lockout/tagout procedures and requirements described in 1915.89 to ensure employee safety.
• If a tag is used, the employer must ensure that the tagout system provides equivalent safety to a lockout whenever possible (for example, by combining tags with additional physical means of isolation).

A lock or tag may be removed or an unblanking performed only after it is determined that doing so will not create a hazard for employees working on the system, or after the work is completed, following the procedures in 1915.163(a)(1) and 1915.89.

• The employer must ensure a safe determination is made before re-energizing or reintroducing pressure, temperature, or flow to the isolated system.
• Removal should follow the employer's lockout/tagout procedures and, when appropriate, involve the person who applied the lock/tag or their authorized designee, consistent with 1915.89.

This prevents accidental release of hazardous energy or hot fluid that could injure workers.

The employer must open drain connections to the atmosphere on all dead interconnecting systems so someone can visually observe drainage, as required by 1915.163(a)(2).

• Opening the drains allows employees or supervisors to verify that the system is actually drained and isolated from live systems.
• Visual observation helps detect trapped pockets of steam, hot water, oil, or other media that could cause injury if the system were re-pressurized.
• Ensure appropriate PPE and controls are used when opening drains to atmosphere to protect against burns or sprays.

To "blank" a valve or piping section means to insert a solid physical barrier (a blank) between the dead and live sections so flow cannot pass; yes, blanking with a blind flange or equivalent positive physical barrier is an acceptable method of blanking under 1915.163(a)(1).

• Examples of blanking include installing a blind flange, inserting a spectacle blind, or using a removable spool with a full-face blank.
• The blank must be secured so it cannot be removed accidentally while employees are working.
• Blanking provides a positive physical separation and is often preferred where possible because it reduces the risk of accidental reintroduction of a hot medium.

The employer is responsible for ensuring the determination that it is safe to remove locks/tags or unblank valves is made, and that determination should follow the procedures in 1915.163(a)(1) and the lockout/tagout requirements in 1915.89. The employer may assign this duty to a competent or authorized person.

• A competent or authorized person—someone capable of recognizing hazards and specifying protections—can make or verify that determination. See OSHA’s letter clarifying the role of a competent person in shipyard operations at https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18.
• The person removing the lock/tag should follow site procedures and, when possible, be the person who applied the device or their authorized designee, consistent with 1915.89.

A "dead system" is the section of piping that has been isolated, drained, and rendered safe for work, while a "live system" is any piping or equipment that still contains pressure, flow, or hazardous temperature; this distinction is the basis for the isolation and blanking requirements in 1915.163(a).

• Practically, a dead system means valves are secured and blanked and drains are open so no hot medium can reach the work area.
• A live system may be under pressure, heated, or otherwise able to introduce hazards into what is intended to be the dead system unless proper isolation is in place.
• The standard requires positive physical measures (lock/tag and blanking) to prevent a live system from re-energizing a dead system while employees are exposed.

Yes — the isolation and shutoff valves that connect the dead system with any live system(s) must be secured, blanked, and then locked or tagged prior to work, as stated in 1915.163(a)(1).

• Securing usually means positioning the valve to the closed state and using physical measures to prevent unintended movement.
• After securing and blanking, a lock or tag meeting 1915.89 requirements must be applied to prevent reactivation.
• These steps are required to protect employees from the direct escape of steam, hot water, oil, or other hazardous media.

The employer should verify drainage by visual observation of the open drains until no further flow or hazardous material is seen, as required by 1915.163(a)(2).

• Observe clear flow from the drain outlet or use an appropriate indicator (for example, cooled liquid discharge or absence of steam).
• Maintain observation until confident that no hazardous pockets remain. Consider keeping drains open and monitored during the job, and use PPE to protect against splashes or steam.
• If visual confirmation is difficult, consult a competent person to recommend additional measures (e.g., additional venting, monitoring devices), consistent with employer responsibility under 1915.163.

This visual check prevents accidental re-pressurization of a pocketed hot medium while employees are exposed.

If valves are welded instead of bolted, the employer must secure at least two isolation and shutoff valves and then lock or tag them in accordance with 1915.163(a)(1), so welded valves alone are not sufficient without the required redundancy and lock/tag controls.

• The rule specifically calls for "at least two" secured isolation valves when welding replaces bolting to provide redundancy.
• Even with welded valves, blanking and lock/tag procedures per 1915.89 must be followed.

This reduces the risk of inadvertent flow from a live system into the area where employees are working.

Yes — locks and tags must be applied in accordance with the lockout/tagout requirements in [1915.89], as required by 1915.163(a)(1).

• 1915.89 contains the shipyard-specific lockout/tagout rules that explain procedures, responsibilities, and necessary controls.
• Employers should integrate the piping isolation procedures of 1915.163 with the site’s broader lockout/tagout program to ensure consistent, safe practices.

The employer must secure and blank all isolation and shutoff valves that connect the dead system with any live system(s) and open drain connections to the atmosphere on all of the dead interconnecting systems for visual observation of drainage, as required by 1915.163(a)(1) and 1915.163(a)(2).

• Treat each interconnection as a potential source of re-pressurization; secure and blank each connection, then lock or tag per 1915.89.
• Open and visually monitor drains on every dead interconnecting system until clear to ensure no trapped hot medium can migrate into the work area.

This comprehensive approach avoids unexpected flow into the isolated section from any connected live source.

Employers should provide appropriate PPE, control the drainage path, and use procedures that minimize exposure to hot liquid or steam when opening drains to atmosphere, consistent with the requirement to open drains for visual observation in 1915.163(a)(2).

• Provide heat-resistant gloves, face shields, and protective clothing as needed to protect against burns or splashes.
• Position drains so the discharge is directed away from personnel and work areas, and use shields or catchment where practical.
• Use remote or controlled venting if available and appropriate; consult a competent person if the drain poses a high hazard (see https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18 for guidance on competent person responsibilities).

Although 1915.163 specifically addresses hazards from the direct escape of steam or high-temperature media, the same principles of securing, blanking, and lock/tagging isolation valves and opening drains are sound controls for other hazardous media and should be used when employees could be exposed to toxic releases; see 1915.163(a).

• The language of 1915.163 focuses on high-temperature media, but employers have a general duty to protect employees from hazardous exposures; applying equivalent isolation measures is a prudent and often required control.
• If toxic substances are involved, also follow any applicable shipyard toxic substance rules and consult a competent person to select appropriate controls (see https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18 about competent persons).

No — 1915.163 requires securing and blanking the isolation and shutoff valves and then locking or tagging them; administrative controls alone are not sufficient for the physical isolation specified by 1915.163(a)(1).

• The regulation calls for physical measures (securing valves and blanking) to prevent the escape of hot media.
• Administrative controls like signs or written procedures should complement, not replace, the physical isolation, and lock/tag procedures in 1915.89 should be followed.

Relying only on administrative controls increases the risk of accidental reactivation and worker injury.

The person who performs securing, blanking, locking, or tagging should be trained and authorized by the employer to perform those actions and should be competent to recognize hazards and implement required protections, consistent with the responsibilities discussed in 1915.163(a)(1) and OSHA guidance on competent persons (see https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18).

• Training should cover the employer’s procedures for isolation, blanking, lockout/tagout per 1915.89, hazard recognition, and safe drain/venting practices.
• Employers may assign the work to an authorized worker or competent person who can recognize hazardous conditions and specify necessary protections, as explained in the competent person letter at https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18.

Proper training and authorization reduce errors in isolation and protect workers from hazardous releases.

If a valve cannot be physically locked, the employer must use other means that achieve equivalent safety — for example, blanking the line, using a locking device installed on the valve, or following the alternative controls allowed by [1915.89] — and document those measures per 1915.163(a)(1).

• Install a valve lock or collar designed to fit the valve stem, or place a blind flange or spectacle blind to provide a positive physical break in the piping.
• Apply a tag in accordance with 1915.89 and add additional physical barriers or controls to reduce risk.
• Consult a competent person if standard lockout devices cannot be used to determine an acceptable method of equivalent protection (see https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18).

Locks or tags must remain in place until it is determined that removing them will not create a hazard to employees working on the system or until the work is completed, consistent with 1915.163(a)(1).

• The lock/tag must not be removed prematurely; removal should follow the employer’s lockout/tagout procedures and applicable rules in 1915.89.
• Any reassessment or removal should be done by the person who applied the device or an authorized designee, and only after ensuring the system can be safely re-energized or re-pressurized.

This prevents accidental introduction of hazardous energy or fluids while employees remain exposed.

If visual observation of drainage is not possible, the employer must take alternative measures to ensure the dead interconnecting systems are fully drained and safe, such as redirecting drains to visible locations, using temporary observation fittings, or employing monitoring by a competent person, while following 1915.163(a)(2).

• Consider installing temporary vent/drain points that discharge to an area where visual confirmation is possible.
• Use mechanical or electronic indicators (pressure gauges, temperature sensors) and verify isolation with a competent person if direct visual observation is impractical.
• Document the alternative measures and ensure personnel are protected by appropriate PPE and procedures; consult the competent person guidance at https://www.osha.gov/laws-regs/standardinterpretations/2016-04-18 if needed.

The goal is the same: reliably confirm the system is safe before work continues.

Yes — the securing, blanking, and lock/tagging requirements of 1915.163(a)(1) and the drain observation requirement of 1915.163(a)(2) apply whenever employees may be exposed to the direct escape of steam, hot liquids, oil, or other high-temperature media, regardless of the job’s duration.

• Even for short-duration tasks, physical isolation (securing and blanking) and lock/tag procedures must be used to protect workers.
• Employers should plan for and provide the necessary devices and PPE for any maintenance or repair that could expose workers to hazardous releases.

Consistency prevents accidents that often occur during brief, seemingly routine operations.

Employers must coordinate so that all parties understand which valves are secured, which blanks are installed, and who applied locks/tags; the isolation and lock/tagging must meet 1915.163(a)(1) and 1915.89.

• Establish a written or verbal handover procedure that documents which systems are isolated, who applied locks/tags, and who is responsible for removal.
• Ensure each employer’s workers know not to remove another employer’s lock/tag and that a supervisory or competent person coordinates lock removal and system reactivation.
• Use joint safety meetings and visible labeling of isolated systems to prevent confusion and accidental reactivation.