Storage and Terminaling: Safe Cleaning

Nov. 1, 2009
Experts list and analyze ways to safely enter and clean floating roof tanks, including protection measures around sumps

LES Bente of Don Miller & Associates Inc. said he didn't mind airing his “dirty laundry” if someone could benefit from it.

During a presentation entitled “Safe Cleaning of Floating Roof Tanks: Protecting Around Sumps,” Bente described an incident in which a worker suffered a leg laceration after falling into a sump. The presentation was made at the International Liquid Terminals Association's 2009 Annual International Operating Conference in Houston, Texas.

Bente said his company had been asked to braze and blast the floor of a tank to get it ready for a magnetic flux leakage test. He said they had an unusual circumstance: There was only one means of ingress and egress — a 24” shell manway near the sump — because the other manway was blocked with AC ducting. The large sump was identified with barricade tape, but there was poor visibility and ventilation.

“Our workers were in an area where they had pretty poor visibility,” he said. “They had localized lighting but not enough to light all of the inside. One of the workers was leaving and fell in the sump and had a laceration to his leg that required stitches. It was not classified as a lost-time accident, but it was OSHA-reportable.

“We realized we had identified where the sump was, but had not done anything to engineer the hazard out or manage it. So we came up with a method of barricading the sump. We built a barricade using tubular scaffolding and made an orange construction fence. It becomes not impossible, but a lot less likely, that someone will fall into the sump.”

He listed these hazards that have a potential to cause head injuries: pantagraph shoe hangers “head knockers”; emergency overflows; IFR pontoons; automatic gauge float sumps; roof drain sumps and piping; and other low-hanging obstructions.

He said there are a number of ways of eliminating or managing the hazard:

  • Proper use of personal protective equipment (PPE): safety glasses, hard hats.

  • Improved lighting. “If a tank has been cleaned and is gas-free, you can put in large halogen lights.”

  • Tag the appurtenance with barricade tape.

  • Paint the hazardous projection.

  • Install “super legs.” “If you're going to replace a tub ring or have multiple shell penetrations to work on, you can fabricate new, longer legs that can be installed while the floating roof is floating, which will put the roof as high as it needs to be and will eliminate low-hanging hazards.”

  • Remove the hazard.

He said OSHA describes the use of lifelines when cleaning tanks in 1910.146 (k) (3): “To facilitate non-entry rescue, retrieval systems or methods shall be used whenever an authorized entrant enters a permit space, unless the retrieval equipment would increase the overall risk of entry or would not contribute to the rescue of the entrant.” In 1910.146 (k) (3) (I), it says, “Each authorized entrant shall use a chest or full body harness, with a retrieval line attached at the center of the entrant's back near shoulder level… . ”

“I'm of the opinion, and most people in the cleaning industry would say, that for most vertical entries, yes, this is a very practical thing,” Bente said. “With underground tanks, sumps, oil water separators, it's good to have the ability to remove the victim from a confined space using a lifeline or cable. They do not work well if you're setting roof legs on a floating roof. Basically, you have this tether on a person, and mechanical retrievable devices do not have cables on them that are long enough to reach across a large tank. A retrieval device is meant to retrieve a victim. It's not designed to have the entrant tethered during the entire time in there. In my opinion, lifelines are rarely needed for horizontal entry.

“It should be left up to the tank owner, but OSHA does give you wiggle room that if it does not add to the overall safety, it need not be used. Example: If you have a tank that has a supplied air-breathing system and lifeline, if he for some reason becomes trapped because something has fallen onto his breathing airline, he can unsnap it and walk out of the tank. If he has a lifeline attached to a D-ring, that's one more thing he has to deal with when he's working on a possible limited air supply, and I'm not proponent of it.”

He said some tools for improving aboveground storage tank safety include: training (videos and on the job); JSA (job safety analysis) or JHA (or job hazard analysis); SPO (safe performance observations); OSHA and American Petroleum Institute (API) publications; and API TES tank entry supervisor certification.

He said API 2015, 2016, 2026, 2207, and 2219 can be ordered from IHS at 1-800-854-7179 or

He said he would recommend anybody who has tank-cleaning operations to familiarize themselves with API 2015, which was re-written in 1997 by a group including Bente. A companion document, API 2016, was developed.

Bente said the API TES certification program was initiated by API Safety and Fire Protection sub-committees, and a task force was set up to develop program criteria, comprising industry experts, owners, and contractors. After a survey of the industry showed broad support, program development started in 2003.

“The examination continues to be a work in progress, just as exams for 653 and other API certification programs are,” he said.

Bente said there are seven activity areas from TES:

  • Project planning. “You don't want to get out there and get ready to open the tank and realize the floating roof legs haven't been set.”

  • Tank preparation.

  • Ventilation and atmospheric testing.

  • Entry for inspection (initial entry).

  • Tank cleaning.

  • Entry for repair and modification (inspection).

  • Return to service.

He said a safe tank entry workshop is put on a few times a year by Guy Colonna, P.E., division manager of National Fire Protection Association (NFPA), who can be contacted at (617) 984-7435 or [email protected].

“This is not a prep course for TES,” Bente said. “If you're a tank owner with an inspector or cleaning contractor and would like to improve the qualifications of some people, this is a good program.”

It's a two-day interactive seminar that provides the following benefits: recognize confined spaces and their hazards; learn best practices and procedures per 2015/ 2016 NFPA 326; ensure safe tank entry for cleaning, maintenance, and repair; select, maintain, and use atmospheric monitoring devices; and document hazard assessment and evaluation on permits.

Temporary Support

In “Temporary Support of Floating Roofs,” Kenneth L Erdmann of Matrix Service Inc defined the issue by saying work typically will place loads onto floating roofs or move floating roofs; floating roofs and supports are typically in a corroded condition; and if an unprotected roof drops, severe injury or fatalities can occur.

“Floating roof incidents strike all levels of owners and manufacturers,” he said. “

A wide variety of companies of various sizes, sophistication, and knowledge base have been struck by this hazard. Companies with and without procedures to address this have been affected. This is a common concern that should be addressed outside of the competitive environment.

“While API does provide a recommended practice which addresses temporary support of floating roofs, API-653 has no mention of the dangers of floating roof support failures while performing various under roof repairs. Floating roof support incidents will always occur. Work practices must ensure these future incidents do not result in personal injuries.”

He listed these owner's responsibilities:

  • Know your equipment. “What types of floating roofs do you have? What condition is your equipment in? Are your specifications addressing the equipment being repaired?”

  • Have required safe work practices. “Understand the dangers of working under certain floating roofs. Know the required temporary supports for this equipment.”

  • Ensure that the work is being done with proper support. “Do not assume the contractor is taking care of it. Keep safety issues outside of other contractual combative topics. Make sure all personnel involved with the project are aware of the dangers and requirements. Do not assign to a safety rep.”

  • Share the risk, share the cost. “Cribbing and supporting roofs takes time and has cost.

Owners must ensure safety, cost, and schedule are properly prioritized.”

The manufacturer's responsibilities:

  • Have safe work practices in place. “Address all types of equipment. Cover various hazards and failure modes. Customize practices to each job as needed.”

  • Train employees on safe practices. “All should know the magnitude of the danger and the required measures that must be taken. Make support a part of standard field equipment.”

  • Accept owner participation. “Use owner requirements and safety audits to help hold self accountable. Reinforce with employees that this is a joint effort, not a competitive or combative topic. On safety topics, use all of the eyes and ears you can.”

He said floating roof potential failures include: vertical collapse or failure of a leg or group of legs; partial collapse or failure of the floating roof components; failure of jacking equipment or temporary supports while jacking; and spiraling of roof resulting in dropping of the entire roof.

“Pan roofs provide less rigid constraint for legs so that movement can more easily initiate,” he said. “Pontoon roofs and double deck roofs provide more rigid leg restraint but also have much more potential energy. All steel floating roofs should be considered equally at risk of spiral collapse.”

He said that with a vertical collapse, a leg or group of legs collapses, either by local overloading or leg deterioration. If a leg buckles, some space may be left under the roof. If the leg pin area of a sleeve ruptures, the local area will free fall and can cause a domino effect.

A component failure typically is an aluminum floating roof problem, he said. Components deteriorate over time and lose support or pontoons take on product. When floating, all is neutral. When on legs, the weight of the product bears on the connection, resulting in failure. It's more of a “falling apart” failure than a total global failure.

He said a failure of jacking equipment or a temporary support is more common on steel roofs, with pontoon and double decks most common. The jacking process or method can lead to the problem.

“Unique roof designs are a concern as they may be much heavier than expected,” he said. “Roof rigidity can contribute, resulting in picking up much more load from a single jack point. If the temporary support is not cribbing, its capacity must be well known.”

A spiral or dropping of the roof is most common on steel roofs, with all steel roofs being susceptible.

“Applied loads, roof movement, or local failures get the ball rolling,” Erdmann said. “Once the roof starts moving, inertia takes over. Rotational resistance that is intact will greatly reduce the likelihood of a dropping roof, but localized failure can still occur. The type of rim seal can affect roof resistance to moving. This is the most common source of fatality of all roof failures.”

Erdmann said the progression of repair may place the roof in susceptible conditions at various times. The worker must ensure temporary support is adequate for each condition of the roof. Common repairs leading to problems: jacking (replacing legs, installing striker places); replacing seals; and replacing guide poles.

Jacking considerations:

  • Know the jacking device and capacity.

  • Pay attention to temporary supports, location, and capacity. Should be near jack point or symmetric with jack point. Should be of similar strength as jack support.

  • Shimming of the roof can lead to failure. If shimming, always shim evenly.

  • Stiffness of the roof will change its behavior. One jack may lift half of the roof load.

  • Air bag use may not be appropriate. Never place weight onto an air bag. Never use an air bag on top of a jack stand.

  • Jacking may shift the roof or cause other support to break free.

  • When jacking roofs, be cautious of shimming under existing legs.

  • When adding cribbing layers to stacks or when shimming under legs, always block up by the same amount at each stack or leg.

  • Capacity of supports should always be similar to capacities of jack.

  • Never use an air bag on top of a jack stand.

  • Never set a weight onto an air bag. Only lift off of supports or lower onto supports.

  • Use air bags to lift the entire roof.

  • Never max out the lift of an air bag.

Safe tank entry

In “Safe Tank Entry,” Jeff Powell of Flint Hills Resources said that with tank/area preparation, a diesel flush reduces lower explosive levels, benzene levels, total hydrocarbon levels, and time for de-gassing.

He said perimeter control establishes boundaries to assist in the controlling of entry of unauthorized personnel and ignition sources, and PPE requirements. Perimeter control is set up before the tank is opened. Perimeter control may shrink or expand during the tank project based on atmospheric monitoring data, or other risks you may want to mitigate.

“Eight bolts are initially removed with an impact and replaced with new bolts and nuts,” he said. “New bolts are properly torqued. Remaining bolts are removed with impact leaving the eight new bolts. The eight bolts are then removed with hand tools. Paint is removed from the manway to ensure a good bonding surface. Magnetic bonding cables are attached to the manway and tank. Continuity is checked. Remaining bolts are removed with impact leaving the eight new bolts. Seven of the eight bolts are then removed with hand tools, leaving one bolt at 3 o'clock or 9 o'clock. The manway then can be swung open.

About the Author

Rick Weber | Associate Editor

Rick Weber has been an associate editor for Trailer/Body Builders since February 2000. A national award-winning sportswriter, he covered the Miami Dolphins for the Fort Myers News-Press following service with publications in California and Australia. He is a graduate of Penn State University.