久久综合久久自在自线精品自,午夜肉伦伦影院无码,999视频精品全部免费品,伊人伊成久久人综合网小说

Some steel plant design and construction of the basic requirements

When installation of steel at a negative temperature, pay attention to the deviation caused by temperature changes in the dimensions of the steel structure. Such as construction steel at room temperature is installed at negative temperatures, we should take measures to adjust the bias.

2
Start at negative temperature steel, open-hearth should be accepted or oxygen converter steel Q235, 16Mn, 15MnV, 16Mnq and 15MnVq steel. Steel should guarantee fight toughness. Q235 steel should have -20 & # 176; D, other should have -40 & # 176; D qualified guarantee.

3
Use of negative temperature steel welding with welding rod, wire, at a preset intensity to meet the requirements of the premise, should be used in low yield strength, toughness against low hydrogen electrodes, an important structure can receive high toughness ultralow hydrogen type electrode.

4
Before using alkaline electrode necessary for baking products manufactured in accordance with the provisions of the certificate. After baking qualified, stored at 80 to 100 & # 176; D within the oven, when used out on the insulation barrel, used with the check. Negative electrode temperature should be re-exposed more than 2h baking. Baking times the electrode should not exceed 3 times.

5
Welding flux required prior to use baking factory certificates in accordance with a moisture content of not greater than 0.1%. At negative temperature welding, flux reuse interval shall not exceed 2h, otherwise it is necessary to re-baked.

6
Cover with carbon dioxide gas welding, purity not less than 99.5% (by volume), moisture content should not exceed 0.005% (by weight). When using bottled gas, the inner pressure is lower than 1N / mm2 should be discontinued. When used at negative temperature, check the lip there is no ice jams.

7
High-strength bolts, ordinary bolts should be product certification, high-strength bolts should be re-inspection of torque coefficient, the axial force at negative temperature before using to meet the requirements.

8
Coating steel used should meet the negative temperature brushing performance requirements prohibit the use of water-based paint.