Technical measures for welding and connection of t

Technical measures for welding and connection of process pipelines

the construction site of the heating pipe replacement project in Xingnan District 1, 3 and 6 is located in Xingnan community, oil production plant 5, Honggang District, Daqing City, with convenient transportation. The planned construction time is from May 12, 2010 to October 30, 2010, with a total construction period of 133 days. The construction stage from June 1 to June 30 is outside the heating. This measure is specially formulated to ensure the welding quality and worker safety

the construction unit of this project is Xingnan project management center, the peripheral property of Daqing Oilfield Mining Division, and the design unit is Daqing Oilfield Wanfang engineering technology. Taking the East extension line of a city subway line 2 under construction as an example, because the East extension line is adjacent to Nanjing landscape Avenue, the project puts forward higher requirements for landscape, which also makes Nanjing subway adopt U-shaped beams for viaducts, and integral unit plates for ordinary box girder sections, And reserve the conditions for the installation of fully enclosed sound barriers. The design institute and the construction unit install three places for Daqing Oilfield Engineering Construction Co., Ltd

2 compilation basis and quantities

2.1 construction drawing heat-10051

2.2 construction standards and specifications

(1) GB code for construction and acceptance of industrial metal pipeline engineering

(2) GB code for construction and acceptance of field equipment and industrial pipeline welding engineering

(3) CJJ code for construction and acceptance of urban heat supply pipe engineering

2.3 quantities

1 Sf-j06 rigid polyurethane foam pipe 10447m

3 preparation work

3.1 the pipe entering the site must have the factory quality certificate or material re inspection sheet before it can be used

3.2 the welding rod or welding wire shall have the factory certificate of conformity, and the coating of the welding rod shall not fall off or have obvious cracks

3.3 the welding rod shall be dried for a long service life as required before use. J422 welding rod is used in this project. The drying temperature of the welding rod is ℃, and the insulation is h. The welding rod after alkali drying is put into the ℃ incubator, and it can be taken as soon as it is used. The welding rod used on site must be placed in the insulation cylinder, and it can be taken as soon as it is used. The welding rod needs to be dried again for more than 4H at room temperature, and the number of repeated drying should not exceed twice

3.4 colorful strip cloth and steel bars are used as sheds on the working platform to prevent wind and rain. During site construction, colorful strip cloth and steel bars are also used as sheds to prevent wind, rain and fire

4 construction scheme and technical measures

4.1 welding method

the pipeline of the project adopts manual arc welding

4.2 specific welding measures

4.2.1 weld layout

4.2.1.1 the distance between the center line of the pipe butt weld and the edge of the support and hanger shall not be less than 50mm

4.2.1.2 the center distance between two adjacent butt welded junctions of the pipe shall meet the following requirements:

when DN ≤ 150mm, it shall not be less than the outer diameter of the pipe

when DN ≥ 150mm, it should not be less than 150mm

4.2.2 groove processing

4.2.2.1 V-shaped groove is used for pipe groove

4.2.2.2 the pipe groove can be machined by mechanical method or cut by oxyacetylene flame, but the oxide skin on its surface must be removed and the convex and concave parts that affect the welding quality must be ground flat

4.2.2.3 before welding, the oil, paint, scale, rust, burr and galvanized layer on the groove surface and groove edge that can reduce the zinc content and improve the anti-corrosion effect at the same time shall be removed, and there shall be no cracks, interlayer and other defects

4.2.3 pipe assembly

4.2.3.1 in order to prevent welding cracks and reduce internal stress, forced assembly should be avoided

4.2.3.2 for the assembly of pipes and fittings with the same wall thickness, the inner wall should be flush, and the inner wall misalignment requirement: it should not exceed 20% of the wall thickness and not more than 2mm