焊接螺旋风管需要注意的问题：

The problems that need to be paid attention to in welding spiral duct are:

1、焊前准备

1. Pre welding preparation

(1)根据板厚形式，采用机械加工、等离子孤切割或碳弧气刨等方法下料加工坡口，为了避免飞溅金属损伤，在使用碳弧气刨和开坡口和手工电弧焊接时，应在坡口两侧涂上石灰粉。

(1) according to the thickness of the plate, the cutting groove is processed by mechanical machining, plasma soliton cutting or carbon arc gas planer. In order to avoid the damage of spatter metal, lime powder should be coated on both sides of the slope when using carbon arc gouging and opening groove and hand arc welding.

(2)坡口形式宜采用V 形坡口，要采用较小的焊接电流，这样可以防止不锈钢产生晶间腐蚀。

(2) the V groove should be adopted in the groove form, and the smaller welding current should be adopted, so that the intergranular corrosion of the stainless steel can be prevented.

(3)为了满足接头具有相同的性能，应遵循“等成分”原则来选择焊接材料，同时要注意接头中的铁素体不能太多，这样是为了增强接头抗热裂纹和晶间腐蚀能力。

(3) in order to meet the same performance of the joint, the "equal component" principle should be followed to select the welding material, while the ferrite in the joint should not be too much, in order to enhance the heat resistance and intergranular corrosion resistance of the joint.

(4)应采用严格的定位焊，遵循“短而厚”、“点焊不焊透”的原则。

(4) strict positioning welding shall be adopted, following the principle of "short and thick" and "spot welding without penetration."

2、焊接技术要求

2, welding technical requirements

(1)手工电弧焊时焊机应采用直流反接，氩弧焊时应采用直流正接。

(1) when manual arc welding is done, DC welding should be adopted for welder, and direct current connection should be adopted during argon arc welding.

(2)在焊接前，应将焊丝用不锈钢丝刷掉表面的氧化皮，并用丙酮清洗，然后进行烘干，随取随用。

(2) before welding, the welding wire should be brushed with stainless steel wire to remove the oxide scale on the surface and cleaned with acetone and then dried.

(3)打底焊时焊缝厚度应尽量薄，这样利于与根部熔合良好；收弧时要成缓坡形，如有收弧缩孔，应用磨光机磨掉。必须在坡口内引弧熄弧，熄弧时应填满弧坑，防止弧坑裂纹。

(3) the thickness of the weld should be as thin as possible, so that it is good for the fusion with the root; when the arc is closed, it should be a gentle slope, such as an arc shrinkage cavity, and the use of a polishing machine. The arc must be extinguished in the groove. When the arc is extinguished, the arc should be filled to prevent crater cracks.

(4)为了防止碳化物析出敏化及晶间腐蚀，应严格控制层间温度和焊后冷却速度，所以要求焊接时层间温度控制在60℃ 以下。

(4) in order to prevent the precipitation of carbides from sensitization and intergranular corrosion, the interlayer temperature and the post weld cooling rate should be strictly controlled, so the interlayer temperature should be controlled below 60 degrees.

(5)在施焊时尽量使用氩弧焊摇把技术，该技术能很好的控制焊层表面颜色以及成形，焊接效果比较理想。

(5) use argon arc welding crank technology as far as possible during welding. This technology can control the surface color and forming of welding layer well, and the welding effect is ideal.

螺旋风管应避免在风管焊缝及其边缘处开孔。最后一步就是焊接后，应注意清除焊缝处的熔渣，并用不绣钢丝刷或铜丝刷刷出金属光泽，再用酸洗膏 进行酸洗钝化，最后用热水清洗干净。

The spiral duct should avoid opening holes at the weld of the wind pipe and its edges. The last step is to remove the molten slag at the weld, and brush out the metallic luster with non embroidered wire brush or copper wire. Then the acid wash ointment is used for pickling and passivation. Finally, it is cleaned with hot water.