Coal Boiler

Coal Boiler

Pellet Boiler

Sources : pellet boiler

Water Tube Boiler System Design

Steam Boiler

Steam Boiler

All repairs must be acceptable to the governing code jurisdiction (such as NBIC), therefore all methods of repair must have written approval from the Chief Inspector or Authorized Inspector. The guideline to flush patch can be obtained from RD-2060a Flush Patches of NBIC.
Carry out hardness test (DT) on the bulge area to determine extent of defect. Mark out the boundary line of the defective section to be cut out based on acceptable tensile strength obtained. Use Vickers Hardness test (HV) to test for the metal strength of carbon steel. The method of repair is called “flush patch”, which means the shell is cutout around the failure in elliptical or rectangular, and a piece of new boilerplate rolled to correct curvature is inserted with the edge of original shell and patch butt-welded. For rectangular shape, provide accurate radius as square corners shall be avoided.
Refer the manufacturer’s blueprint on the material specifications of the shell and the patches shall be made from the material that is equal in quality and thickness to the original material. The edge shall align without overlap. Weld preparation to be double “vee” with an included angle of 60o to 70o. The gas tungsten arc welding (GTAW) shall be used for the initial pass joining the patch to shell. The balance of the weld shall be manual shielded metallic arc welding using low hydrogen electrodes confirmed to ASME Code Sect IX.
Weld the inside first, then back gouge on the outside. Grind the sound metal before continuing the welding on the outside. Grind flush the accessible surface, and after completion of welding, visually check for weld undercut and repair if necessary. Refer the manufacturer’s blueprint on the NDT used during construction, and normally the weld on flush patch of shell is 100% radiographed. Acceptance of weld is in accordance with ASME Code or BS 2970 code. Post weld heat treatment (PWHT) is to be done to relieve the residual stress on the heat affected zone (HAZ). Carryout hydrostatic test on the boiler. Test pressure shall be 1.5 times the design pressure. The holding time is 10 minutes.


Air conditioning and heating systems are also known as HVAC, now-a-days which means Heating, Ventilating and Air conditioning. This term mainly started in early second century when the Roman cities used it as a central heating system or a Hypocaust. Then this term got fame in Industrial era and now it is used as an integrated system for keeping the climate cool.
Uses of HVAC:
The first and the primary use of HVAC are to regulate the room temperature, humidity and air flowing to an amount suitable for the body to sustain in that environment. A suitable range of this environment should be ensured as it minimizes health risks which are:
1. A very humid atmosphere unable the body’s activity to perform the function of evaporation of sweat and also causes fatigue due to which it is difficult for the body to perform various tasks
2. 2. Hypothermia and Heat Stroke are two major breakdowns caused in body when unhealthy surroundings affect people’s thinking abilities.
3. Temporary HAVC units can also be used in case of emergency. It is used in extreme weather conditions for keeping the climate cool or hot and healthy. In many cases, it is the only invention used for survival and work. For example, a crewman working in a tunnel needs HVAC to keep the temperature at a suitable level.
4. In many situations HVAC have been used for saving lives. One incident occurred in Texas where a girl was fallen in a tunnel and was lodged there for a couple of days. So what the rescuer did was, they pushed a hose for her to respire fresh air and in the meanwhile found a way to rescue her.
5. Temporary HVAC are also used in schools, institutions, offices, homes, buildings and many other areas where it is necessary for temperature and humidity to be controlled.
Three Types of temporary HAVC units:
The three types of HVAC are which are mainly used everywhere are:
1. Generators:
In the present era, almost everyone requires a generator for carrying on their work because fossil fuel is getting becoming led in quantity day by day. This is mainly used in those countries where power grid is to expect to be down for a much longer time period. Generators are used for providing lighting and thermo-regulation.
Due to its massive use, generators now are manufactured in various models, brands and qualities. Customers are given an ample choice to select whatever type of generator they require for their usage.
2. Chillers:
HVAC system has introduced chillers for keeping the specific areas cool. They are large sized so they are mainly used in industries and for commercial uses. HVAC chillers require thermal, condensers, compressor, evaporator and stabilizers so as to perform the function in the best applicable way as possible.
3. Boilers:
Two types of boilers have been introduced by HVAC. That is Steam boiler and Hot water Boiler and whoever have used them, have praised their excellence.

Articles Source : steam boiler