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阀门的安装指南
 二维码 6
发表时间:2017-12-05 10:36

低温焊接与银钎焊

务必记住所推荐的阀门的用途是什么,并对所应用的环境进行分析,这样才能决定最适合于安装什么样的阀门。在安装正确的阀门之前,为了防止损坏阀门,移动泵车并保证充分发挥阀门的工作性能,请阅读一下安装指南。

1.先沿着垂直方向切割管道,并修整、去除毛刺,测量管径。

2.使用纱布或钢丝刷清除管道和切割部位,使其金属表面发光发亮。建议不要使用钢丝绒。

3.在管道的外面和焊接罩的内部涂上焊剂,焊剂必须完全覆盖焊接表面。请有节制地使用焊剂。

4.要确保阀门处于开启状态。先对管道加热。尽可能多的将热从管道传递到阀门。避免延长阀门本身的加热时间。

4a. 银钎焊的方法:

对需要进行钎焊的部件进行组装。如果允许涂上焊剂的部件处于直立状态,那么焊剂中的水分会蒸发掉,而干燥的焊剂很容易脱落,致使暴露的金属表面容易被氧化。在进行连接组装时,要将管道插入管套直到遇到阻挡为止。组装是要保证有稳固的支撑,使得整个钎焊操作过程中能够保持在直线位置。

注:对于1英寸或更大公称通径的阀门,一次性将连接部件加热到所需温度比较困难。为了在整个大面积上保持正常的温度,通常情况下需要两个焊枪。建议对整个管套区域进行适当的预热。建议采用乙炔火焰对连接部件进行加热。首先从离阀门1英寸的地方开始对管道进行加热,然后围绕着管道短距离上下交替对管道进行火焰烘烤,并以适当的角度旋转管道,避免烧穿管道。火焰要连续运动,不允许停留在某一点上。

在阀门的套筒底座用火焰进行烘烤。加热要均匀,用火焰对阀门及管道进行火焰烘烤的过程要延续到阀门上的焊剂不再发出声音。不要对阀门过度加热。

当焊剂变成液态并且在管道和阀门上呈现半透明状态时,开始将火焰沿着连接部件的轴线进行进退烘烤,以保持连接部件、特别是阀门套筒底座部位的热度。

5.使用适量的焊料:自吸泵车如果使用线状焊料,那么对公称通径为3/4英寸的阀门就要采用3/4英寸的焊料,等等。如果使用的焊料太多,那么有些焊料可能会流过管道阻挡部位,并堵塞密封区域。在安装连接部件时,可以看到焊料和钎焊合金继续流动

5a. 银钎焊法:

将焊线或焊杆点在阀门里的管道套座上。当焊杆或焊线进入连接处时要将火焰从其上面移开。当合金流进连接处时,要前后移动火焰。达到适当的温度后,合金将迅速容易地流进管道外壳和阀门套管之间的空间。连接处被充满后,就会看到焊接合金的边缘。

6.当焊料处于粘滞状态时,用刷子把多余的焊料清除干净。焊料冷却后,将一条嵌条环绕在阀门的端口。

银钎焊

  如果采用不同的钎焊材料,其钎焊连接的强度并不见得很好,强度大小取决于管道外壳与阀门套管之间正常的、大范围的清洁维护工作。银钎焊的阀门套管的内部直径的机械公差和表面光滑度要求非常精确,以确保有足够的附着力。

注意:在清理和清除过程中,应该细心的观察清洗介质的残留物。在已经弄脏或不正确清洗的表面上进行钎焊,焊接效果就很难令人满意,因为银钎焊合金并不会流过或粘接在氧化物上,而油污的表面及暴露的、容易氧化和导致空隙和杂物排斥焊剂。

螺纹连接

  硬渣、污物或任何外部物质在管道内积累都可能妨碍阀门的工作效率并严重损坏阀门的关键部件。必须用空气或蒸气对管道内部进行彻底清洗。

当对管道进行攻丝时,要测定管道螺纹的尺寸和长度,避免将管道塞满阀座和阀瓣。彻底清洗螺纹末端,清除任何有害的钢或铁沉淀物。如果要时焊接更牢固,就要使用特氟隆带或管道粘接剂。在管道螺纹上只能少量使用管道粘接剂,但是在阀门螺纹上绝对不能使用管道粘接剂。不要让任何管道粘接剂流入阀体内,以避免损坏阀瓣和阀座。

安装前,切断通过阀门的流体,以使阀门工作正常。安装前要完全关闭阀门。将扳手套在靠近管道的六角螺栓头上避免可能产生的变形。加药装置安装阀门后,要支撑住管道:下垂的管道会使阀门产生变形而导致失败。

法兰连接

  为了确保正确进行阀兰连接安装,需要遵循如下几个步骤。首先细心地清洗连接处,然后,在底座部松散地装上两个或三个螺栓。接着,小心的将垫片插入连接处。底部螺栓有助于对垫片进行定位,并保持恰当的位置。然后插入螺栓要采用交叉旋紧的方式,不要采用环绕旋紧的方式,这样有助于消除过于集中的压力)。在正常使用一段时间后,要检查核对所有的螺栓是否旋紧,并进行必要的再旋紧。

SOLDERING AND SILVER BRAZING

Analyze the application to determine which valve is best suited for installation, keeping in mind the service for which the valve is recommended. Before installing the correct valve, review the installation instructions to prevent damage to the valve and assure its maximum efficiency.

1.Cut tube end square. Ream, burr and size.

2.Use sand cloth or steel wire brush to clean both tube and cut to bright metal. Steel wool is not recommended.

3.Apply flux to outside of tube and inside of solder cup. Surfaces to be joined must be completely covered. Use flux sparingly.

4.Be sure that valve is fully open. Apply heat to tube first. Transfer as much heat as possible through tube into valve. Avoid prolonged heating of valve itself.

4a. Silver Brazing Method:

Assemble parts to be brazed. If fluxed parts are allowed to stand, the water in the flux will evaporate; and dried flux is liable to flake off, exposing metal surfaces to oxidation. Assemble joint by inserting tube into socket hard against the stop. The assembly should be firmly supported so that it will remain in alignment during the brazing operation.

NOTE: On one inch and large valves, it is difficult to bring the whole joint up to temperature at one time. It will frequently be found desirable to use a double tip torch to maintain the proper temperature over the large area. A mild pre-heating of the whole socket area is recommended. Apply heat to parts to be joined. The preferred method is by oxy-acetylene flame. Heat tube first, beginning one inch from edge of valve. Sweep flame around tube in short strokes up and down at right angles to run of tube. To avoid burning through tube, the flame should be in continuous motion and not allowed to remain on any one point.

Apply flame to valve at base of socket. Heat uniformly, sweeping flame from valve to tube until flux on valve becomes quiet. Avoid excessive heating of valve.

When flux appears liquid and transparent on both tube and valve, start sweeping flame back and forth along axis of joint to maintain heat on parts to be joined, especially toward base of valve socket.

5.Use just enougn solder: with wire solder, use 3/4" for a 3/4" valve, etc. If too much solder is used, it may flow past tube stop and clog sealing area. When joint is filled, a continuous run of solder or brazing alloy will be visible.

5a. Silver Brazing Method:

Apply brazing wire or rod at point where tube enters valve socket. Keep flame away from rod or wire as it is fed into the joint. Move flame back and forth as alloy is drawn into joint. When the proper temperature is reached, alloy will flow readily into space between tube outer wall and valve socket. When joint is filled, a continuous rim of brazing alloy will be visible.

6.Remove excess solder with small brush while plastic, leaving a fillet around end of valve as cools.

SILVER BRAZING

The strength of a brazed joint does not vary appreciably with the different brazing materials, but depends to a large extent upon the maintenance of proper clearance between the outside of the tube and the valve socket. The interior dimensions of silver brazing valve sockets are machined to the closest tolerances and finished smooth to promote full capillary attraction.

NOTE: Care should be observed in cleaning and in removing residues of the cleaning medium. Attempting to braze a contaminated or improperly cleaned surface will result in an unsatisfactory joint. Silver brazing alloys will not flow over or bond to oxides. Oily or greasy surfaces repel fluxes, leaving bare spots which oxidize and result in voids and inclusions.

THREADING

Grid, dirt or any foreign matter accumulated in the pipe can hinder efficient valve operation and seriously damage vital valve parts. Thoroughly clean pipe internally with air or steam.

When threading pipe, gauge pipe threads for size and length to avoid jamming pipe against seat and disc. Thoroughly clean threaded end to remove any harmful steel or iron deposits. For a good joint, use teflon tape or pipe dope. If pipe dope is used, apply sparingly on pipe threads, never on valve threads. Do not allow any pipe dope into valve body in order to avoid damage to disc and seat.

Before installation, check line of flow through valve so that valve will function properly. Close valve completely before installation. Apply wrench to hex next to pipe and guard against possible distortion. After installation of valve, support line; a sagging pipe line can distort the valve and cause failure.

FLANGED

There are several steps to follow to make sure that a flanged joint will be properly assembled. First clean the joint carefully. Then loosely assemble the joint by putting in the bottom two or three bolts. Then carefully insert the gasket into place. The bottom bolts will help locate gasket and hold it in position. Then insert the rest of the bolts into place and tighten all of the bolts evenly - not in rotation, but by the cross over method to load the bolts evenly and eliminate concentrated stresses. The bolts should be checked for tightness after an appropriate interval of use and retightened if necessary.



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