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A Boiler: The Explosive Potential of a Bomb
Acoustic Emission Examination of Metal Pressure Vessels
Anatomy of a Catastrophic Boiler Accident
Austenitic Stainless Steel
Basic Weld Inspection - Part 1
Basic Weld Inspection - Part 2
Black Liquor Recovery Boilers - An Introduction
Boiler Efficiency and Steam Quality: The Challenge of Creating Quality Steam Using Existing Boiler Efficiencies
Boiler Logs Can Reduce Accidents
Boiler/Burner Combustion Air Supply Requirements and Maintenance
Carbon Monoxide Poisoning Preventable With Complete Inspection
Combustion Air Requirements:The Forgotten Element In Boiler Rooms
Creep and Creep Failures
Description of Construction and Inspection Procedure for Steam Locomotive and Fire Tube Boilers
Ensuring Safe Operation Of Vessels With Quick-Opening Closures
Environmental Heat Exchangers
Factors Affecting Inservice Cracking of Weld Zone in Corrosive Service
Failure Avoidance in Welded Fabrication
Finite Element Analysis of Pressure Vessels
Fuel Ash Corrosion
Fuel Firing Apparatus - Natural Gas
Grain Boundaries
Heat Treatment - What Is It?
How to Destroy a Boiler -- Part 1
How to Destroy a Boiler -- Part 2
How to Destroy a Boiler -- Part 3
Identifying Pressure Vessel Nozzle Problems
Inspection, Repair, and Alteration of Yankee Dryers
Inspection, What Better Place to Begin
Laminations Led to Incident
Lay-up of Heating Boilers
Liquid Penetrant Examination
Low Voltage Short Circuiting-GMAW
Low Water Cut-Off Technology
Low-Water Cutoff: A Maintenance Must
Magnetic Particle Examination
Maintaining Proper Boiler Inspections Through Proper Relationships
Microstructural Degradation
Miracle Fluid?
Organizing A Vessel, Tank, and Piping Inspection Program
Paper Machine Failure Investigation: Inspection Requirements Should Be Changed For Dryer Can
Pipe Support Performance as It Applies to Power Plant Safety and Reliability
Polymer Use for Boilers and Pressure Vessels
Pressure Vessel Fatigue
Pressure Vessels: Analyzing Change
Preventing Corrosion Under Insulation
Preventing Steam/Condensate System Accidents
Proper Boiler Care Makes Good Business Sense:Safety Precautions for Drycleaning Businesses
Putting a Stop to Steam Kettle Failure
Quick Actuating Closures
Quick-Actuating Door Failures
Real-Time Radioscopic Examination
Recommendations For A Safe Boiler Room
Recovering Boiler Systems After A Flood
Rendering Plants Require Safety
Repair or Alteration of Pressure Vessels
Residential Water Heater Safety
School Boiler Maintenance Programs: How Safe Are The Children?
Secondary Low-Water Fuel Cutoff Probe: Is It as Safe as You Think?
Short-Term High Temperature Failures
Specification of Rupture Disk Burst Pressure
Steam Traps Affect Boiler Plant Efficiency
Steps to Safety: Guide for Restarting Boilers After Summer Lay-Up
Stress Corrosion Cracking of Steel in Liquefied Ammonia Service - A Recapitulation
Suggested Daily Boiler Log Program
Suggested Maintenance Log Program
System Design, Specifications, Operation, and Inspection of Deaerators
Tack Welding
Temperature And Pressure Relief Valves Often Overlooked
Temperature Considerations for Pressure Relief Valve Application
The Authorized Inspector's Responsibility for Dimensional Inspection
The Effects of Erosion-Corrosion on Power Plant Piping
The Forgotten Boiler That Suddenly Isn't
The Trend of Boiler/Pressure Vessel Incidents: On the Decline?
The Use of Pressure Vessels for Human Occupancy in Clinical Hyberbaric Medicine
Thermally Induced Stress Cycling (Thermal Shock) in Firetube Boilers
Top Ten Boiler and Combustion Safety Issues to Avoid
Typical Improper Repairs of Safety Valves
Wasted Superheat Converted to Hot, Sanitary Water
Water Maintenance Essential to Prevent Boiler Scaling
Water Still Flashes to Steam at 212
Welding Consideration for Pressure Relief Valves
Welding Symbols: A Useful System or Undecipherable Hieroglyphics?
What is the Best Welding Process?
What Should You Do Before Starting Boilers After Summer Lay-Up?
Why? A Question for All Inspectors

Proper Boiler Care Makes Good Business Sense:Safety Precautions for Drycleaning Businesses

John Hoh
National Board Assistant Director of Inspections

Summer 1996  

Category: Incidents 


Summary: The following article is a part of National Board Classic Series and it was published in the National Board BULLETIN. (4 printed pages)



Saturday was cleanup day at the small drycleaner's. Every week, the horizontal return tubular (HRT) boiler was drained, flushed and prepared for the next week's work. This Saturday, however, the boiler operator was interrupted during his final steps. He performed every task except refilling the boiler.

This boiler was set to start automatically early on Monday mornings. The prescribed time arrived; the burner engaged. When the owner arrived to open the business Monday morning, she found the local fire department at her back door and the severely overheated remains of her boiler.

Luckily, there was no explosion, since there was no water in the boiler. Also, firefighters on the scene knew they should never spray water on an overheated boiler, so they closed the gas supply valve on the outside of the building and allowed the boiler to cool gradually. They stayed on-site to prevent any structural fires that might have developed as a result of the overheated boiler.

What happened?

The low-water fuel cutoff should have prevented the burner from engaging, but the electrician improperly wired the control into the burner circuitry. The boiler had been operating in a potentially hazardous manner for several months. Had the owner requested an inspection, the boiler inspector would have tested the operation of the low-water fuel cutoff and, in this case, would have found it inoperable.

The uninsured boiler was a total loss. Both tube sheets had numerous cracks in the ligaments (the tube sheet material between the tube holes) and the bottom portion of the shell was severely deformed due to excessive heat.

This loss cost the owner of the drycleaning business several thousand dollars for replacement of the boiler and business lost while waiting for the replacement boiler installation. A boiler inspection and jurisdictional certificate would have cost less than $50.

The National Board of Boiler and Pressure Vessel Inspectors has files full of photographs, newsclippings and official reports from serious accidents. Frequently and unfortunately, facilities that use boilers, like drycleaners, are the subject of these accidents. Since drycleaning plants need an adequate supply of steam, all have a boiler of some sort on the premises. Boilers are workhorse devices that sometimes are neglected for years, possibly decades, with no apparent maintenance. This neglect, whether intentional or due to lack of understanding, can have terrible consequences.

Depending on the operation, a drycleaning plant will have one or more boilers under its roof. A drycleaning plant will also contain other pressure vessels such as a typical water heater and an air compressor tank. While these pressure vessels are potentially hazardous and are subject to inspection in most jurisdictions, this article focuses on the boiler.

We all know how a boiler operates. Water is contained within a vessel and is heated by gas, electricity or some other fuel. As the water heats, it creates pressure and steam. Boilers are equipped with devices to control operating pressure, and safety valves that should allow pressure relief when safe operating limits are exceeded. But lack of routine inspection and lack of proper maintenance are widespread.

The National Board reports the following two causes at the top of the 2000 list of incidents*:



  • Failure of cutoff system to operate when water gets too low.


  • Operator error or poor maintenance.

    * At time of posting, latest year for which statistics are available.


Prevention Through Inspection

In the incident described above, a boiler inspector would have seen the problem and made recommendations to repair the boiler before that fateful morning. Thus, a costly and potentially dangerous accident would have been prevented.

Typically, insurance companies and city, state or provincial governments (jurisdictions) require boiler and pressure vessel inspection on some regular interval. The National Board trains and commissions boiler inspectors who perform both safety inspections and accident investigations. But there are many boiler and pressure vessel system-users who have not had their systems inspected or licensed. It's no surprise that often, the uninspected systems are also poorly maintained.

Everyone Can Help

Perhaps the best route to ensure boiler and pressure vessel safety is to practice installation and maintenance functions that meet both jurisdictional requirements and national standards.

Five preventive steps can help:


  • Equipment installation: Install only boiler and pressure vessel equipment registered with the National Board. Such equipment will be manufactured in accordance with the ASME Boiler and Pressure Vessel Code. Most jurisdictions mandate National Board registration.


  • Replacement parts: Purchase first-quality replacement parts (new or rebuilt) for any boiler or pressure vessel repair or maintenance effort.


  • Training: Adequately train all personnel who regularly use or maintain a boiler or pressure vessel. Do not allow a general maintenance person to assume the responsibilities for day-to-day operation of any boiler or pressure vessel unless that person has had specific training.


  • Safety testing: Establish a regular, periodic safety-testing program for all boilers and pressure vessels. Develop a checklist. Make sure everyone who encounters the boiler or pressure vessel knows the danger signs and whom to call for immediate help.


  • Repairs: Require that all welded repairs be performed by National Board "R" stamp holders who are properly trained and qualified to repair boilers and pressure vessels. Such items have very specific repair protocols that help prevent accidents.


Each drycleaning plant can establish a simple safety program. For example, look for a certificate of inspection on or near each boiler. The certificate should indicate the number of pounds of pressure under which the system can safely operate. A quick glance at the pressure gage can instantly identify a potential danger.

As part of routine maintenance, open and clean boilers. Test pressure relief valves to make sure they are functioning properly. Move clutter, stored items and combustible substances far away from a boiler, so that overheating of these materials is not possible. Flammable liquids should not be stored in the same area as a boiler. Clean and dust the room that houses the boiler, and prevent nesting or breeding sites for pests.

Whenever you spot a potential problem, call the chief boiler inspector within your jurisdiction. For a listing of chief boiler inspectors, consult the Members page on the National Board Web site. Note the inspection certificate number and the jurisdictional number assigned to the boiler. With these numbers, the chief boiler inspector can determine the boiler's location and any other information necessary to perform an inspection.

If There Is An Accident . . .

During the first minutes on an accident scene, one of the biggest risks with boilers is the high temperatures that may exist. Water or condensate hitting superheated metal can cause instant bursts of steam or further explosions. Also, one breath of superheated steam can damage the lungs and cause permanent breathing problems. If a problem does occur, local emergency personnel, such as firefighters, are your first line of defense. A call to the chief boiler inspector within your jurisdiction will be vital to any accident investigation.

Good preventive maintenance and periodic inspection result in cost savings. Good safety practices make sense in a liability context. Since boilers are an integral part of the drycleaning business, provide the routine maintenance and obtain the periodic inspections that will prevent accidents or problems in the future.



Editor's note: Some ASME Boiler and Pressure Vessel Code requirements may have changed because of advances in material technology and/or actual experience. The reader is cautioned to refer to the latest edition of the ASME Boiler and Pressure Vessel Code for current requirements.


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