What is the In-Service Inspection Requirements for the Water Tube Boiler Inspection? The In-Service Inspection code for your water tube boiler is ASME Section VII. The inspection regulation is different from one location to another location by regulated jurisdiction. In some states, the inspection by an authorized inspector of the insurance company is mandatory. Generally, the states that have mandated “S” stamp for manufactured boilers, have also mandated in-service inspection by authorized inspection agencies. The API also has a recommendation practice, API RP 573, for the inspection of fired boilers and heaters. Most of these practices and recommendations are similar to the ASME Code Section VII Recommended Guidelines for Care of Power Boilers. During inspection and probable repair, other codes and recommendation practices might be used. Some of these are API RP 577, API RP 571 and ASME Code Section IX. Please note that your water tube boiler is “S” stamped and you need to do repair, you have to use a Repair Organization holding an “R” Stamp from the National Board Inspection Code. What are the Important Points in the Water Tube Boiler Inspection During shutdown? Water Tube boiler inspections are categorized as follows: Inspection of Internal Sections Inspection of refractories in the floor, walls and roofs of economizer, generation and superheater sections Inspection of refractories in man-ways, inspection and explosion doors Inspection of explosion and inspection doors for corrosion, warpage, and assurance for proper sealing contact and performance Inspection of refractories steel supports, beams and hangers Inspection of Tubes Supervision and inspection of tubes outside cleaning process such as walnut hulls or dry ice blasting or washing with water Thickness measurement of tubes and headers Tube hangers inspection in economizer, generation and superheater section Inspection of tubes in economizer, generation and superheater for bowing, sagging, oxidation, splitting, external corrosion and deposit, leaking roll and bulging. Inspection of fin tubes for mechanical damage, distortion and corrosion Inspection of skin thermocouple weld joint in superheater section Inspection of tubes weld joints Replication test on superheater tubes (if necessary) Sampling of a tube in superheater for sectioning and corrosion analysis Inspection of tubes replacements Supervision of tubes hydrostatic testing Inspection of Burners Inspection of refractories around the burners Burner belonging components inspection such as burner tile, burner impeller, air register and damper Thickness measurement on fuel gas and fuel oil piping systems Inspection of air test process on the flexible hoses for fuel gas system Inspection of Soot Blowers Inspection of blowing tube for deformation and breaking Inspection of supports and their welding joints Inspection of blower tubes replacement (if necessary) Inspection of Boiler External Parts Inspection of paint and insulation Inspection external surface for bulging and mechanical damage Inspection of expansion joints in the ducts for any warpage, tearing and burning Inspection of thermowells for erosion and cracking Inspection of gasket seating area Inspection for performance of explosion and inspection doors (proper opening and closing) Inspection of Stack Thickness measurement in different locations Inspection of thermowells for cracking and burning Inspection of refractories Inspection of concrete foundation and anchor bolts Inspection of earthing system Inspection of guillotine frame and valves for corrosion and performance Inspection of paint surface Inspection of end nozzles Inspection of Steam Drum Inspection and supervision of cleaning process Inspection of thermowells for corrosion, erosion and cracking Inspection of nozzles, manway weld joints for corrosion and cracking Inspection of internal surface for fouling, discolorations and cracking Inspection of longitudinal and circumferential weld joints Inspection of demister pads for corrosion, cracking and deformation Inspection of internal ladder and supports for corrosion and deformation Internal inspection of tubes by borescope Inspection of chemical injection and blowdown holes Inspection of gasket seating area for corrosion and erosion Inspection of reinforcement plate and welding joints Inspection of supporting plate and structure Inspection of small bore connections for corrosion and mechanical damage Inspection of Silencer Inspection of cleaning process Inspection of ceramic blankets and perforated plates Inspection of weld joints Inspection of silencer heads and components Hydronic Piping Systems Posted by Dave on June 19, 2014 Hydronics is the use of water as the heat-transfer medium in heating and cooling systems. A hydronic piping system is used to circulate chilled or hot water with the connections between the piping and the terminal units made in a series loop. The terminal units are the heat exchangers that transfer the thermal energy between the water and the spaces to be cooled or heated. Hydronic systems may be used for both a chilled and a heated water loop with chillers and cooling towers used separately or together as a means to provide water cooling, while boilers heat the water. Types of hydronic piping systems are: 1. The Series Loop – This system is aptly named because all of the units are in series, and one loop is formed. In this system the entire water supply flows through each terminal unit and then returns to the generator and pump. Although it is a simple arrangement, this setup has its disadvantages: o To maintain or repair any terminal unit, it requires a shutdown of the entire system. o The number of units is limited because in heating systems the water temperature continually decreases as it gives up heat in each unit in series. That can cause a low temperature in the far units in the system which may not provide adequate heat for comfort. The series loop arrangement is basic, inexpensive and mostly used for residences. 2. One-Pipe Main – With this system, each terminal unit is connected by a supply and a return branch pipe to the main. By locating valves in the branch lines, each unit can be separately controlled and serviced. In this system, like in the series loop, if there are too many units the heated water going to the far units may be not sufficient for room comfort. 3. Two-Pipe Direct Return – This is generally used for larger systems and consists of two mains. One main is used for supply and one main is used for return. This system is more expensive than the one-pipe main and series loop, but it allows each terminal unit to be separately controlled and serviced because the supply water temperature to each unit is the same. The twopipe system is called direct return because the return main is routed to bring the water back to the source by the shortest path. 4. Two-Pipe Reverse Return – Here we have a supply and a return that are equal in length and size. The first terminal supplied is the last terminal returned and vise-versa, making it is easy to balance the flow rates. Combination arrangements can also be made to create a three-pipe or four-pipe system. In the threepipe arrangement, simultaneous heating or cooling can be made available. There are two-supply mains, one circulating chilled water, the other hot water. Three-way control valves in the branch to each terminal unit will determine whether the unit receives hot or chilled water and the return main receives the water from each unit. However, the three-pipe system can waste energy because the return main mixes chilled and hot water. In this mixing process, the chilled water is warmed and the hot water is cooled, which results in extra heating and cooling in the boiler and/or chiller. The four-pipe arrangement is expensive, but it separates two-pipe systems – one for chilled water and one for hot water. Therefore, no mixing occurs making it an ideal arrangement to avoid wasted energy.
