环境温度低于0 焊接作业指导书
Welding instruction when environment temperature below 01. 适用范围Scope
规定了我厂在造船舶船体结构普通钢，高强度钢对接，角接焊缝预热要求。
This instruction specifies requirements for hull structure normal strength and higher strength steels butt joint and fillet joint preheating.
2. 引用标准Reference standard
IACS NO.47 Shipbuilding and Repair Quality Standard (Rev.4, Aug.2008)
3. 预热、测量工具Pretesting and measurement equipment
3.1 采用氧乙炔割炬烘焙方法对焊缝两边母材进行预热。
Base metal both sides of welding to be preheating by oxyacetylene Welding & Cutting torches baking method.
3.2 采用点温计进行温度测量。
Temperature to be measured by point temperature gauge.
4. 预热要求及温度测量点要求 Requirements of preheating and temperature measurement points
4.1对于普通钢（A,B,D,E），当环境温度低于-5 时，需要对焊缝两边的母材进行预热，最低预热温度大于20 ；
When environment temperature is below -5 , it shall be preheated for normal strength steels (A, B, D, E), and the lowest preheating temperature shall be more than 20 .
4.2对于高强度钢（AH32-EH32,AH36-EH36），当环境温度低于0 ，需要对焊缝两边的母材进行预热，最低预热温度大于20 。
When environment temperature is below 0 , it shall be preheated for higher strength steels (AH32-EH32, AH36-EH36), and the lowest preheating temperature shall be more than 20 .
4.3 为了避免局部预热过度，预热温度不能大于250 。
In order to avoid local excessive preheating, preheating temperature can not exceed 250
4.4 温度测量点 Temperature measurement points
温度测量一般在正对着焊工的工件表面，
The temperature measurement shall normally be made on the surface of the workpiece facing the welder
4.4.1 宽度测量区域如图一所示：当母材板厚不大于50mm时，测量范围为距坡口边缘4倍板厚，且不超过50mm的距离处测量；当板厚大于50mm时，测量范围应位于至少75mm距离的母材或坡口任何方向上的相应位置（当焊缝两边母材厚度有差异时，以厚板的一边为基准）。
Width measurement areas see Figure-1: When the base metal thickness is not more than 50mm, the area is at the distance of 4t (It is the thickness of base metal), but not more than 50mm from the longitudinal edge of the groove; however when the thickness exceeds 50mm, the requirement temperature shall exist in the parent metal for a distance of at least 75mm or as otherwise agreed in any direction from the joint preparation (when thickness on both sides of weld is difference ,the thicker to be as the base).
4.4.2 焊接过程中，在焊接方向上取500mm和1m作为测量点。
The distance of 500mm and 1m from welding point along welding direction shall be made as measurement point during welding.
5. 操作要求及测量要求 Operation and measurement requirements
5.1 焊接之前应对需要焊接的区域进行整体性的烘干，除去焊缝坡口及焊缝两边母材表面的水蒸气。
In order to remove the water vapor from the surface of weld groove and base metal ,it shall baking all the required welding area before welding
5.2 点温计的测量点应距焊缝母材表面垂直距离100mm左右。
The measurement point of point temperature gauge shall be about 100mm vertical distance to base metal surface.
5.3开始焊接位置应按照4.1-4.2项的要求对焊缝两边母材进行预热，预热温度应大于20 （初始预热温度）;测量点取距焊缝坡口50mm（母材厚度不大于50mm）和100mm(母材厚度大于50mm)。 Base metal shall be preheated according to the item 4.1 and 4.2 when starting to weld, the preheating temperature shall be more than 20 (original preheating temperature),the measurement point shall be at distance of 50mm( for t 50mm) and 100mm(t>50mm) from the longitudinal edge of the groove.
5.4 焊接过程中，在4.4项的测量区域内随机取点，在焊接方向上距焊接点500mm测量，焊缝两边母材表面温度应大于20 ；在焊接方向上距焊接点1000mm测量，焊缝两边母材表面温度应大于0 ；如不满足要求应按照5.3项焊前进行预热。Random points to be temperature measured according to the measurement area in item 4.4 when welding. A distance of 500mm from welding point along welding direction the temperature on base metal surface shall be more than 20 ; and a distance of 1000mm from welding point along welding direction the temperature on base metal surface shall be more than 0 . When it can’t meet the requirements it should be preheated according to the item 5.3.
6.其他Other
6.1 初始预热温度的定义Definitions of original preheating temperature
初始预热温度是指任何焊接操作开始之前，焊接区域内工件的瞬时温度。
Original preheating temperature: the temperature of the workpiece in the weld zone immediately prior to any welding operation.
6.2 对于多层多道焊，对于第一层焊接完应使用绝热保温材料进行保温，确保第一层焊温度不能小于0 。
The first-pass weld should be warm protected with insulation material after finishing, and making sure the temperature of the first-pass weld shall be not less than 0 .
7．检测记录 Measurement record
生产车间应专人安排人做好记录，检测记录见附录表格。
Workshop shall make the measurement record according to the annex table.
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