By Jim Kolbus, Clark-Reliance Boiler Trim Products
Boilers represent a significant capital investment for any company, making routine inspections all the more necessary for proper operation and to help reduce the chance of accidents. Preventative action can decrease boiler risks and lower liability insurance costs at the same time.
Expanding technology for boiler installations has brought with it greater boiler complexity. More automatic “watchdogs” such as electronic monitoring devices and other control components are now used to improve operation.
However, too often these automatic features lead plant personnel to become complacent and mistakenly assume it’s safe to ignore the equipment.
One critical step toward boiler safety and optimum performance is conducting a boiler inspection either annually or every six months, depending upon the type, style, size and age of the boilers. This simple procedure helps you spot possible trouble areas, reduce downtime and prevent harm to personnel and equipment.
A boiler inspection is routinely handled by an independent technical specialist. This inspector will check out areas that affect the boiler’s structural integrity. Qualified plant personnel with working knowledge of the boiler can perform a general inspection and spot trouble areas long before a technical specialist is called.
A simple checklist helps to improve the effectiveness of these routine inspections and helps to ensure proper operation with minimal downtime. The checklists below cover the most common violations that field inspectors encounter when dealing with low pressure steam boiler installations.
Checklist for Water Level Indicators
- The lowest visible part of the water gage glass is at least one inch above the lowest permissible water level recommended by the boiler manufacturer.
- A boiler operating at up to 400 PSIG has at least one direct-reading water-gage glass in service at all times.
- A boiler operating at pressures greater than 400 PSIG has either two direct-reading water-gage glasses or two remote level indicators on continuous display and one direct-reading gage.
- The boiler has at least one direct-reading glass, no matter how many indirect magnetic water level indicators are installed.
- Bi-color ported type water gages equipped with a functional illuminator are needed for two-color display of steam and water.
- There is at least a one-inch overlap for transparent type glass gages with multiple sections to maintain visibility of the actual water level.
- All trip alarm points are within the visible range of the gage glass.
- The boiler has a control that cuts off the fuel supply when the steam pressure reaches an operating limit, which is less than the maximum allowable pressure.
- The scale on the dial of low-pressure steam gage is graduated to no less than 30 psig or more than 60 psig.
- Ball check valves in upper and lower fittings open by gravity, and the lower ball check valve rises vertically to its seat.
- The ball seat in the upper fitting is a flat seat with either a square or hexagonal opening.
- There are no leaking, valved off or mis-applied gages. If valved-off, find out why.
- Water gage valves do not have leaking stems or nipple packing.
Checklist for Water Columns
- There is a one-inch minimum connection size from boiler to the water column.
- There is a 3/4-inch minimum connection size from the boiler to a remote level indicator.
- Gage glasses required by code are connected directly to the shell or drum of the boiler or to an intervening water column.
- The lower edge of the steam connection between a water column and level indicator is not below the highest visible water level on the gage glass.
- The upper edge of the water connection between a water column and level indicator is not above the lowest visible water level in the gage glass.
- The water column piping has a cross or equivalent fitting at every right angle turn to help in cleaning.
- Sludge or sediment must be cleaned from the water column or connecting pipes to reduce false water level indications.
- If there are shut off valves between the steam boiler and water column, they must be of through-flow design and physically locked open.
Checklist for General Boiler Areas
- There is a minimum clear space of 18 inches on all sides of the boiler. As a minimum, all other sides comply with the boiler manufacturer’s installation instructions for clearances to combustible materials.
- The boiler manufacturer’s installation instructions, operating manual and safety guidelines are in an accessible location.
- There is an acceptable level of noise next to the boiler and an acceptable duration of exposure.
- The storage method of chemicals used in the treatment and cleaning process is in compliance with state EPA guidelines.
- No fuel leaks from fuel tanks.
- There are fire extinguishing devices nearby and they have been recently inspected.
It is important for boiler industry personnel to have access to a current set of applicable codebooks/jurisdictional laws, such as Section I and IV of the American Society of Mechanical Engineers’ (ASME) Internal Boiler and Pressure Vessel Code.
To ensure confidence and verify that these important devices are functioning properly, go through this checklist and handle required maintenance while adhering to the ASME Boiler Code.
If any of these checklist items are not cleared up, you should immediately notify management or call a certified, independent technical inspector.
Author: Jim Kolbus is product manager for Clark-Reliance Boiler Trim Products.