某个具体的管件的压力额定值是什么？
What is the pressure rating of a given fitting?

最常见原因：
MOST COMMON:

1. 流速 - 流体流动太快了。建议流速：60^oC热水的流速为0.0508~0.0762米/秒，冷水流速为0.127~0.2032米/秒。
   Velocity - fluid is moving too fast. Recommendation: 2-3 fps (0.0508-0.0762 m/s) hot water 140^oF, 5-8 fps (0.127-0.2032 m/s) cold water.
2. 湍流 - 切割管道时留下的毛刺使流体产生旋转作用，导致局部侵蚀，从而最终造成故障。
   Turbulence - burrs left on the cut tubing causes a tumbling effect causing localized erosion and eventual failure.
3. 侵蚀性水 - 容易在固定装置上造成蚀损斑或绿锈。造成蚀损斑的侵蚀性、硬井水通常含有硫酸盐和氯化物溶解总固体，pH值范围在7.2至7.8之间，而且二氧化碳的含量很高，也存在溶解氧。造成绿锈的软酸性水通常具有更强的腐蚀性。低碱、低矿物质含量、pH值低于7的流体应该避免。
   Aggressive Waters - tend to cause pitting or green staining of fixtures. Aggressive, hard well waters that cause pitting typically are found to have total dissolved solids including sulfates and chlorides, a pH in the range of 7.2 to 7.8, a high content of carbon dioxide gas and the presence of dissolved oxygen gas. Soft acidic waters that cause green staining typically tend to be more corrosive. Low alkalinity, low mineralization, pH levels of 7 or lower should be avoided.

较少见的原因：
LESS COMMON:

1. 焊剂腐蚀 - 在进行连接作业时焊剂使用过多可能会造成残留物，从而导致局部腐蚀。焊剂使用应该节俭，而且系统应该进行充分的冲洗。
   Flux Corrosion - using too much flux when making joints can potentially leave residue and cause isolated corrosion. Flux should be used sparingly and system adequately flushed.
2. 电解 - 杂散电流（直流电）；管道没有适当接地。
   Electrolysis - stray (D.C.) current; inadequate grounding for the piping.
3. 沙或其他固体颗粒 - 可能会造成侵蚀/腐蚀。如果流体介质含有固体颗粒，必须保持低速流动状态。
   Sand or other solid particulates - erosion/corrosion problems can occur. Lower velocities must be maintained if solids are present in flow media.
4. 电化腐蚀 - 在环境和材料之间产生的电化作用对材料造成的破坏。
   Galvanic Corrosion - destruction of a material by electrochemical interaction between the environment and the material.

如果不采用防止腐蚀的绝缘隔离装置，能将不同的金属（如铜和铁）连接在一起吗？
Can dissimilar metals (i.e., copper and iron) be joined together without use of dielectric insulators to prevent corrosion?

大多数情况下不用采用绝缘隔离装置也可以成功地将不同金属（铜/铁/钢）连接在一起。需要考虑的因素有：
In most situations dissimilar metals (copper/iron/steel) can be joined successfully without using dielectric insulators. Factors to consider:

1. 两种金属的成分。
   The composition of the two metals.
2. 通过两种金属的流速。
   The rate of liquid flow past the two metals.
3. 水中的化学物质可能会强化或破坏保护层。
   Chemicals in the water which could enhance or destroy protective films.
4. 两种金属的相对面积 - 除非较活跃的材料（钢）表面面积比更惰性材料（铜）的表面面积的5%还要小，否则不需要绝缘隔离装置。（由于电化腐蚀造成的故障非常罕见，只有在很恶劣的环境下才会发生。）
   The relative areas of the two metals - unless the surface area of the less noble (steel) material is less that 5% of the more noble (copper) material, the need for a dielectric separator is not needed. (Failures due to galvanic corrosion are very unusual and only occur under very strict conditions.)
5. 当地有关规定要求。
   Local code requirements.

应该做下列工作：
The following should be done:

1. 确保接地装置（配置在连接尾管和螺纹连接件区域）不会受到刻刮。
   Make sure the ground-joint (mating area of unions tail and thread pieces) are free of nicks and scratches.
2. 用食物级硅树脂喷剂喷涂接地装置区域，或者涂敷蜂蜡以加强密封效果。
   Spray the ground-joint area with a food grade silicone spray or apply bees wax to enhance seating.
3. 确保管道对齐，不要在接地密封位置出现横向应力。
   Make sure alignment of line does not put lateral stress on the ground-joint seal.
4. 确保过量的焊料（滴状）不会接触到接地区域。
   Make sure that excess solder (droplets) do not reach the ground-joint area.