Bolt heating rod parameters
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(I) The turbine bolt electric heater shall meet the following requirements:
1. The raw materials used for the electric heater shall meet the following requirements:
① The composition of the insulating material magnesium oxide shall comply with HG3-1294-80 "Magnesium Oxide";
② Magnesium oxide must be dried before use;
③ The heating material used for the electric heater is 0Cr27A17Mo2 high-resistance electric heating alloy wire, with an operating temperature of 400°C, and technical requirements according to GB1234 "High-Resistance Electric Heating Alloy";
④ The protective tube material of the electric heater is 1Cr18Ni9Ti heat-resistant stainless steel tube. Its technical requirements are according to YB804 "Stainless and Acid-Resistant Seamless Steel Tubes". Use of other materials shall be agreed upon by the manufacturer and the user;
⑤ After removing burrs from the inside of the protective tube used for the electric heater, clean it with gasoline or kerosene, dry it, and then use it.
2. The finished electric heater shall meet the following requirements:
① The rated working voltage of the
electric heater is 220±20V. DC 100V, low voltage 50V;
② For an insertion length within 1m, the straightness of the centerline shall not exceed φ0.3mm; for an insertion length of 1-2m, the straightness of the centerline shall not exceed φ0.4mm;
③ The diameter deviation of the inserted part is -0.20mm/-0.50mm;
④ The length deviation of the inserted part is ±5mm, the heating length deviation is ±5mm, and the cold end length at the bottom is 25-30mm;
⑤ The electric heater shall heat uniformly during use, and local overheating is not allowed.
(II) When conducting a life test on the electric heater, each heating time is 10-20min. Under intermittent heating conditions, with the total gap between the bolt center hole and the outer diameter of the electric heater being 0.8-1.3mm, the cumulative life shall not be less than 50h.
(III) The connection between the alloy resistance wire and the lead wire shall be firm and reliable, without looseness. The shell must be well grounded.
(IV) After the steel tube of the electric heater is cold-drawn and reduced, its surface shall be inspected by dye penetrant testing or with a magnifying glass of 5 times or more, and there shall be no cracks or other defects. The tube reduction shall be formed in one direction.
(V) The sealing at the cold end of the electric heater shall be tight to prevent moisture from entering and damaging the insulation.
(VI) After the electric heater is manufactured, after one and a half months, its insulation resistance shall be measured at room temperature with a 500V megohmmeter (can be performed at the manufacturer or user site) and shall not be less than 50MΩ.
