Boiler welding and assembly

1.1. Product, its purpose, technical requirements for the product

Steel hot water gas boiler KSVa-0, 8 Gn is designed to produce hot water with a pressure of up to 0.6 MPa with a nominal temperature of up to 90 °C. Automated boiler KSVa-0.8 has a vertical design, is equipped with safety automation and has a high efficiency of 91%.

The automatic control system provides protection and alarm in case of decrease in air pressure in front of the burner, in case of decrease in gas pressure in front of the burner and automation, in case of increased water temperature at the outlet of the boiler, in case of increase or decrease in water pressure at the outlet of the boiler, in case of increase in gas pressure in front of the automation, in case of increased pressure (explosion) in the furnace, in case of extinguishing of the Flame.

Operating conditions of the vessel:

The vessel operates under a pressure of 0.6 MPa at a temperature from -20 to +450 C. The load on the walls of the body is static. The chemical medium is inactive, the speed of water movement relative to the inner surface is quite low. Therefore, friction can be neglected.

Technical requirements for the manufacture of the vessel

The deviation in dimensions during the manufacture of the receptacle shall not exceed:

Shell length +5 mm;

Edge offset:

Longitudinal joints 10% of the wall thickness;

Circumferential joints 20% of the wall thickness;

Based on the operating conditions, we conclude that the most dangerous factor that can lead to the failure of this product is static load. High requirements are imposed on the tightness of the structure, so the vessel should be classified as responsible.

1.2. Characteristics of the product material

The material of the product is Steel st. 3sp. Carbon steels of ordinary quality (GOST 380-88), which are operated in the temperature range (-70.. + 450°C). The type of delivery is long products, which are intended for load-bearing and non-load-bearing elements of welded structures and parts operating at normal and elevated temperatures. Steel sheet is also used. The chemical composition and mechanical properties of this material are given in Table 1 and Table 2, respectively.

Table 1.2.1 Chemical composition of steel according to GOST 380-71 [1, p. 24]

Chemical Properties

Based on its chemical composition, 3sp steel is low-carbon (c<0.24%), pearlitic grade. Steel does not contain chemically active elements.

Table 1. 2.3. Mechanical properties of steel according to GOST 380-71 [1, p. 24]

1.3. Analysis of the potential propensity of a given material to crack formation during welding.

Weldability:

We check the propensity of the weld metal to the occurrence of hot cracks under the most difficult conditions (at the highest level of alloying elements and impurities):