Sound winter preplanning reveals preventive measures to take now that can prepare and protect mills against problems brought on by cold weather
October 2007
By David Johnson and Mark Cooper
Depending on where your mill is located, the approaching winter season may or may not present imminent threats to your business. This article provides loss prevention recommendations that can help facilities prevent costly property damage and avoid unscheduled downtime during the cold weather months.
Circulating just about everywhere throughout the mill, water is the lifeblood of operations in this industry - a critical component both to the process and to fire protection. Yet, its value can easily be taken for granted when mills are not prepared to endure the potential risks associated with winter. Neglecting to guard against these perils with advance planning can freeze production, as well as profits.
Every winter storm has its own inherent twist. Naturally, you can't predict what the upcoming season might bring. However, there are some general preventive measures to take now that will prepare and protect mills against problems brought on by cold weather. Remember: an unprepared, unprotected facility is an easy target for a winter calamity. With sound preplanning, a mill stands the best chance of defending against whatever the upcoming winter season has in store.
Preplanning is a Must
A recent 20-year FM Global study of cold weather-related property damage at pulp and paper facilities showed that freezing of process and fire protection water, together with roof overload caused by snow, ice or hail, accounted for nearly 80% of losses, costing more than $1 million on average per incident. In most cases, facilities located in areas unaccustomed to severe cold and deep snow accumulation suffered most, because they were not equipped to deal with these conditions over an extended period. But while the extreme cold may not be avoidable, the downtime it can cause is preventable.
Each mill should develop a freeze plan, which is a contingency plan that addresses the question "What if cold weather comes?" with a list of all counteractive measures to be taken. The plan should include lines of authority and personnel assignments, specific areas of concern within the plant, priority order of operation and shutdown of equipment, any outside contractors needed to implement the plan and alternative supplies of fuel and power. This plan will enable a mill to respond effectively, rather than desperately, to an emergency situation.
The following sections list key areas that could have an affect on business operations in the event of a freeze-up at a mill. Whether that impact is positive or negative depends on how well a mill incorporates suggested measures into its emergency plan.
Tip 1: Risk Assessment
Determine your mill's exposure. The following questions can help assess a mill's vulnerability to severe winter weather:
- Does your locale usually experience temperate winters?
- Would wind direction or wind chill affect your mill's ability to withstand freezing temperature?
- Has your locale ever experienced long periods of freezing temperature or an accumulation of snow or ice?
- Do you ever shut down operations during the winter holidays?
- Does heat generated by process equipment also supply or supplement building heat?
- Do building temperatures drop when process equipment is shut off?
If you answered yes to any of these questions, then chances are your mill is at an increased risk of loss due to freezing.
Tip 2: Alternate Fuel Supply
Fuel curtailment, primarily natural gas, has been a major factor at pulp and paper facilities during freezing weather. In many cases, mills were asked to reduce fuel use by almost 75%. The ability to switch over to alternate fuel supplies, namely fuel oil and wood/bark chips, can be hampered by problems with otherwise idle fuel equipment. For example, fuel oil systems or instruments can freeze to the point that fuel parameters (e.g., flow, pressure) cannot be controlled accurately. Be sure to:
Check Your Equipment: Oil tanks, pumps, piping, instrumentation, heat exchangers and filling stations should all be inspected for proper operation. If you are expecting otherwise idle heating equipment to be operational when freezing weather comes, confirm it as such in the fall, and again just before the cold snap hits. Also, guard against heat exchanger equipment freeze-up if fuel oil is being used only as emergency fuel and the system is idle for extended periods.
Check Your Inventory: Chip storage, either in piles or in bins, can freeze as well. When mills are able to get chips onto belt feeders, smooth-surfaced belts sometimes do not provide enough surface friction to carry frost-covered chips up relatively steep inclines. If you expect this to be a problem, use ribbed belts instead. Also, be sure to arrange chip and bark fuel supplies for continued operations during inclement weather conditions.
Tip 3: Heat-Trace Critical Process Piping
Protect critical liquid process piping with electrical heat tracing.
Tip 4: Protect the Feed Water Supply
Protect against loss of boiler feed water. Loss of feed water supply can potentially begin a chain of events that will bring the entire mill to a halt. Here are some ways to eliminate this hazard:
On New Construction: Provide enough demineralized feed water storage capacity, considering loss of condensate return, to survive a 24-hour period of uninterrupted plant demand.
On Existing Construction: Provide electrical heat tracing for all outside instrumentation and piping.
Also, provide space heating for the water treatment plant. This provision may include the need for building enclosures as well. Outdoor construction is mill-wide at many locations, making it necessary to protect key areas of the mill against freezing. The water treatment plant is one of those areas, and it should be protected to ensure continuous operations. Heat-traced piping and instrumentation will help the water treatment personnel maintain supplies during freezing conditions.
Tip 5: Safeguard Critical Instruments
Protect the following critical instrumentation and instrument-sensing lines with heat tracing as well as with heated insulated instrument cabinets:
- Feed water controls
- Deaerator controls
- Boiler drum level controls
- Fuel line instrumentation
- Water plant instrumentation
The freezing of instrument-sensing lines and instrument air lines is a problem in most outdoor areas of the mill, especially in the steam plant. Without the boilers online, plant operations will come to a halt and process piping will freeze. Heat tracing vital instruments, such as those mentioned here, will help avoid downstream operating problems.
Also, provide air dryers for instrument air supply. Check the performance of the dryers before, and periodically throughout, the winter season to avoid the freezing of condensate inside instrument air lines.
Tip 6: Test the Protection
Prior to the winter season, test all electrically heat-traced circuits for proper operation to make sure that wiring is intact and that each circuit will respond properly to changing ambient temperatures. Electrical heat tracing is preferred over steam tracing. Idle steam tracing circuits collect condensate and can freeze, rendering the heat tracing ineffective. Where such circuits are installed, make every effort to verify they are in proper working order both prior to and throughout the winter season.
Tip 7: Idle Equipment
Drain and store equipment, such as boilers and piping systems, that will be idle for extended periods. Use a desiccant to keep moisture from building up in equipment. As part of contingency planning, decide what equipment or piping should be drained ahead of time and what equipment should be drained as it comes offline during the freeze.
Tip 8: Training
Add freeze precautions to the operator training program so freeze contingency plans can be expeditiously implemented. Incorporate the information into operating manuals, and conduct special review sessions before winter to inform operators of past problems and prepare them for the upcoming season.
Operating after the freeze condition can be difficult as well. If some instruments and piping freeze and rupture, thawing conditions can lead to faulty instrument readings and subsequent operating upsets. If it is known that the freeze has affected certain instruments, they should be removed from the control loop until they are repaired. Therefore, operators should be alert to these potential problems and ready to take appropriate control actions.
Tip 9: Fire Sprinkler Systems
Freezing of automatic sprinkler systems is a major concern during severe cold weather. Even facilities protected by dry pipe sprinkler systems are susceptible to the same peril as wet pipe sprinkler systems. Frozen sprinkler risers, frozen condensation at low points (where water condensation often occurs) and accidental trips allowing water into the dry pipe systems are all possible.
The key is to keep normally dry piping as dry as possible, and to keep water-filled piping warm enough to prevent freezing. Low point drains should also be checked regularly to prevent freezing. A fire that occurs when automatic sprinkler system protection is out of service can be devastating (see "Weyerhaeuser" sidebar, below).
Because frozen sprinkler piping renders the sprinkler system completely useless, its repair should be given top priority. First, determine how much of the sprinkler system is affected. Lay out hoses (keep them dry) and portable extinguishers. Notify your property insurer and the local public fire service. If only a small section of a system is affected, consider isolating the frozen section and immediately restoring the rest of the system to service.
For larger freeze events, temporarily shut off the sprinkler system, turn up the building's heat, and bring in and safely arrange portable heaters. Be sure to avoid the use of torches, oil and gasoline fuel heaters where building construction or contents are combustible. Don't let haste be the reason a building gets burned down.
Check the following when preparing a facility for cold weather:
- Low points in sprinkler system piping
- Adequacy of heat for dry-pipe valve riser enclosures
- Fire pump rooms
- Water tanks
Tip 10: Emergency Response Team (ERT)
A well-trained ERT that is ready to take action when a cold front is barreling down from the north and stay on the job during and after the storm is essential. When storms loom for extended periods, ERT personnel should patrol the buildings, looking for cold spots, structural damage, large leaks or sprinkler piping breaks. Provide ERT members with phone numbers of outside contractors that can immediately repair breaks in the sprinkler system.
After the storm or cold weather has passed, it is critical to restore impaired fire protection systems quickly. Prohibit hot work operations in areas where automatic sprinklers are being repaired. Remove combustible debris and ban smoking in these areas. Keep an eye out for leaking flammable gas, flammable liquid, live power lines, and structures in danger of falling or collapse. Separate damaged from undamaged goods, and cover equipment and stock to protect it against further exposure.
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On February 5, 1989, an unusually severe cold front from the Arctic settled into portions of the upper northwestern US, plummeting temperatures to nearly zero. For Weyerhaeuser Company's Snoqualmie, WA, plywood plant, the abnormally frigid conditions caused a slew of problems, sparking the largest fire loss in the company's 107-year history. Consequently, this was the last day that 140 employees would ever work at the plant â an unfortunate tragedy that could have been prevented.
The Exposure: Recent plant site revisions had redirected the flow of runoff water in a ditch, which lowered its water level, exposing several sectional valves and portions of fire main. Soil, intended to insulate the main, had eroded throughout the years, and left some parts vulnerable.
What is more, as most of the plant operation shut down, the water flow in the underground main was at a standstill. This lack of flow, coupled with the fact that parts of the main were exposed to the elements, caused those portions of the main to freeze. Due to the sudden burst of subfreezing conditions, the Snoqualmie plant was unprepared to endure such an adverse climate change.
"Nobody really thought twice about it," explains Joel Gaither, property insurance and fire protection manager at Weyerhaeuser. "Specialists conducted their valve inspections in accordance with FM Global and National Fire Protection Agency (NFPA) standards and noted that the fire protection valves were open, but nobody thought twice about the fact that there was an exposed underground fire main in the ditch that no longer had water in it."
The Result: Despite a sprinkler system in perfect working order and a 500,000 gal reservoir of process water, the frozen water in the main prevented the delivery of necessary power to extinguish the small fire that had started in the motor of a forced draft fan on a dryer. Making it worse, when the local fire service arrived minutes later, several unsuccessful attempts to tap the water supply from the plant's surrounding hydrants delayed emergency response to the growing blaze. By the time firefighters found water, it was too late. Sadly, a minor disruption turned into a $33 million catastrophe in the matter of minutes.
Lessons Learned: With winter preparation at the forefront of its property loss prevention program, Weyerhaeuser views its cold weather strategy as "essential" and an approach that "absolutely has to be employed" at its facilities prior to the onslaught of winter.
"The Snoqualmie loss really opened our eyes to the impact of winter weather, because this was something we could have easily prevented," says Gaither. "An ounce of prevention [really] is worth a pound of cure."
To combat the potential risks associated with cold weather, Weyerhaeuser distributes a "winterization" memo in the fall to inform employees of the need to prepare at more than 260 locations in North America now insured by FM Global. The information is then disseminated throughout each mill site to raise awareness and to put contingency plans into action.
"All of our mills get the same brushstroke of alerts, regardless of whether they are located in Saskatchewan or if they're in Georgia," Gaither describes. "This way, we know we are proactively reducing our risk exposure to prevent cold weather-related losses at our mills."
Weyerhaeuser also dedicates a portion of the company's fire protection standards and procedures manual, or "bible on fire protection" as Gaither puts it, to winterization.
"The 1989 fire loss really drove the need for a freeze prevention program to be in place," says Gaither. "Since then, we have not had a major cold weather-related fire loss."
Gaither advises that mills need to take winter seriously to protect their bottom line.
"Planning in advance shouldn't take place when winter has already arrived or when a cold snap is about to," notes Gaither. "It is critical that mills take the time to review their site's winterization preparation points to be ready for the worst-case scenario. Everybody needs to be on guard."
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Dave Johnson, P.E., is operations vice president and engineering manager for forest products operations at FM Global in Dallas, TX. Mark Cooper is a senior account engineer in the company's Stockholm, Sweden, branch.
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