By invitation only: The dangers of confined space

Today’s powerplants are complex engineering triumphs with attention-grabbing geometries, curious nooks and crannies, and sealed entryways. Approaching, and perhaps peering into, a not-normally-accessible area seems attractive. Going further suggests a challenge. But many plant visitors (as well as some full-time employees) may not appreciate just how dangerous these spaces can be.

Today’s heat-recovery steam generators (HRSGs) have many such areas, from the gas-turbine exhaust flange to the stack on the gas side, and from the LP drum to the steam-turbine exhaust hood and condenser on the steam side. Several are (or should be) marked clearly as Confined Space.

Look in all directions. For those authorized to enter, even that first reach or step inside can pose unexpected hazards, as highlighted during a safety session at HRST Inc’s HRSG Academy (January 2016) in San Antonio. Consulting Editor Steve Stultz attended that meeting and wrote this article based, in part, on what he learned there. Referring to Fig 1, the outside opening allows access to an upper crawl space of this HRSG. But looking in beyond the casing, then immediately down, reveals a vertical drop of 60 ft along a finned tube wall (Fig 2).

Confined space Fig 1, 2

It’s not just gravity that could cause the damage. Air moves around, fumes rise, noise travels, and sources of light change, so the unexpected cavity poses many variables and potential dangers to the untutored visitor. So for even the seasoned HRSG worker, short-term lack of attention (or complacency) can lead to catastrophe. The bottom line: Always expect the unexpected.

To some staff and contractor personnel at combined-cycle plants, Confined Space designations and regulations might be less than routine. In the US, confined spaces are regulated by the Occupational Safety and Health Administration (OSHA). Under OSHA 29 CFR 1910.146, gas-turbine enclosures normally are not considered confined spaces (although they are considered so in Great Britain). On the HRSG and condenser side, restricted-area rules and regulations are common, and many areas are clearly defined as Confined Space.

Further, industry experts remind us that:

      • Conditions can change within each HRSG.

      • Designs differ from OEM to OEM.

      • Designs also can differ within the same OEM.

Fire/Safety Specialist Duane Daggers at JLN Associates LLC, Old Lyme, Conn, looks at confined space from a variety of angles, experiences, and training. He is a safety supervisor, rescue team member, and paramedic. Perhaps more important, Daggers holds advanced degrees in safety and leadership, and is well versed in rules and regulations—including OSHA, NFPA, and ANSI. He knows the all-important steps and paperwork.

He also knows that if done properly and with specific purpose, training, guidance, and permits, working within a designated confined space can be a unique and personally rewarding experience. “Complacency is what can get workers injured and killed,” says Daggers. “And with a new generation of employees entering the industry, these seemingly stringent rules and regulations become even more meaningful.”

Confined Space defined. Daggers offers a clear summary of Confined Space: “Any time you unbolt a hatch and have to enter an area not designed for everyday worker activity, it is classified as a confined space.” He also gives the two OSHA-supported definitions which are explained in CFR 29 1910.146.

Non-permit-required confined space is one that does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious harm. When there are changes in the use or configuration of a non-permit confined space that might increase the hazards to entrants, it can be re-evaluated and if necessary reclassified as a permit-required space. Crawl spaces are excellent examples. Under normal circumstances, they pose minimal risk. However, all spaces have the potential to cause injury and often are re-evaluated.

Permit-required confined space is one that is large enough and configured so that an employee can enter and perform assigned work. It has limited or restricted access, and is not designated for continuous occupancy. The space may contain a potentially hazardous atmosphere, it may have limited oxygen content, and it may contain mechanical or electrical equipment, which upon contact or activation may trap, crush, or electrocute the worker.

In Fig 3, the spaces shown are the lower HRSG hatches for the superheater and the HP evaporator. With the doors open a temporary barricade is installed to warn people to not enter, and the various lines for air, welding, and electric are all secured in a corner to reduce trip hazards and keep exit points clear.

Confined space Fig 3

A critical first step for all confined areas is an OSHA-approved lockout/tagout program. Lockout/tagout specifically means the control of hazardous energy. It refers to the practices and procedures necessary to disable machinery or equipment, thereby preventing the release of hazardous energy while employees perform service and maintenance. It happens before anyone enters.

Outage concerns. For most lean-staffed combined-cycle plants, an outage brings contractors and others to the site who, perhaps, are not familiar with unique areas and configurations, changes made since the last outage, and even site-specific nomenclature and rules. Ongoing plant operations could be in abnormal configurations. There can be moments of confusion.

Service providers like JLN can play key roles in the coordination of such events and personnel during any outage. In a well-planned outage, the full-time plant staff can more easily concentrate on the outage activities, maintenance, costs, and schedules.

Regulations from organizations like OSHA also play a critical role in both outage success and worker safety. Training and awareness are full-time jobs at any site. The more common elements that are implemented and enforced, the less likely the confusion or misunderstanding. OHSA, for example, plays a commonly accepted heavy hand in confined-space rules and procedures.

Permits demand focus. Knowing a permit is required means identifying precisely what is within the space and what conditions the workers will face. It means, first, that a hazard assessment is complete. It means, for the contractor, that the host employer can define all elements within all confined spaces, will coordinate entry operations of all work groups (both direct employee and contractor), and will be aware of all permit-space programs implemented on the site.

It also means that all activities should be planned and scheduled in advance. Workers must then complete a work authorization (job safety analysis or JSA) which clearly identifies the scope of their work, potential hazards, and all steps used to control those hazards. Daggers points out that “the confined-space entry permit is specific to the area of work and must contain exact information before any entry.” This includes precise dates and durations. More specifically, Daggers lists the details:

      • Entrants by name.

      • Attendants.

      • Supervisors.

      • Specific hazards.

      • Measures used (lockout/tagout) to isolate the space and control hazards.

      • Acceptable entry conditions.

      • Results of all initial and periodic atmospheric tests, including names and dates.

      • Rescue and emergency services available including equipment and contact information.

The supervisor has a long list of responsibilities, including full understanding of all personal protective and rescue equipment; all hazards; symptoms and consequences of exposure; procedures for terminating entry and canceling the permit; means of summoning rescue services; and procedures for removing unauthorized individuals from the area. The supervisor is also responsible for all attendants.

Attendants enforce the rules. Attendants do much more than check names against rosters. They are trained in confined-space regulations, OSHA requirements, and atmospheric monitoring. Specific tasks are defined further by OSHA.

As Daggers explains, “Attendants must understand all possible hazards including the mode, signs or symptoms, and consequences of exposure. They must understand, watch for and identify possible behavioral effects, while maintaining a constant vigil outside the permit space, and communicating with those inside. Their primary duty is to protect the entrants. And they are fully authorized to remove anyone.”

Atmospheric monitoring is critical. All confined spaces, both non-permit and permit, must have atmospheric testing before any entry, using calibrated direct-reading instruments. Tests include:

      • Oxygen content.

      • Flammable gases and vapors.

      • Potential toxic air contaminants.

Atmospheric testing can be facility-, area-, and operation-specific. Knowing how the facility operates is a key factor in determining what potential contaminants may be within a confined space. Take ammonia for example. The gas side is affected when plants use anhydrous ammonia for NOx reduction. On the steam/water side, plants using seawater for condensing and cooling need to test for organic compounds including ammonia in the condenser waterboxes.

And consider again the opening in Fig 2. Because air and fumes move, knowing the configuration and content of an adjacent space could help determine the type of tests. All areas are then monitored for any changes in the internal atmosphere.

Rescue plan and team. Authorized entry requires an approved rescue plan and certified rescue team. OSHA again has specific requirements for team members, including the following:

      • In-depth training and practice.

      • Knowledge of retrieval methods, and their consequences.

      • Training in first aid and CPR.

A team generally includes a minimum of four medical and rescue trained personnel with a full complement of equipment to establish a safe work zone and perform technical rescue. Each team member wears a complete rescue ensemble in the event all must enter to assist with the rescue. Each must use a chest or full-body harness, or other approved rescue system with a retrieval line. The retrieval line is attached to a mechanical device or fixed point outside the permit space. Also, a mechanical device must be in place to retrieve personnel from vertical spaces more than five feet.

The confined-space rescue team completes the same entry procedures as every other entrant. The team must complete a JSA, ensure lockout/tagout protection, receive approval for entry, and be logged in and out.

It’s in the paperwork. Taking JLN again as an example, trained contractors can become the “eyes and ears” for owner/operators during many tasks and scheduled operations. They can handle confined-space permits, serve as supervisors and monitors, and perform other tasks including rescue. And perhaps more important, they know the rules and control the paperwork.

Safety programs have many names: Safety First, Target Zero, and even Slogans Don’t Save Lives. But all include the personal responsibility to know in advance, to stay alert, to know even the best workers make mistakes, and to stop work when problems arise. Regardless of the name, it’s people looking out for other people, and for themselves.

Speaking for those who make safety a career, Daggers offers the following: “As safety professionals we make sure administrators and workers all have the same safety culture. We don’t stress the importance of safety because it is mandatory, or because we enjoy pointing out mistakes. We make it a point to ensure all workers on the jobsites make it home at the end of their shift.”

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