Causes of pump casing leakage and solutions

For welding cast iron, it is best to use special welding electrodes, such as those from American Universal, as well as MG Company’s electrodes with grades 770, 777, 210, 289, etc

It’s probably a casting defect; use cast iron welding rods and make sure to preheat and maintain the appropriate temperature.

It’s probably a casting defect! Welding cast iron is quite difficult; it is recommended to use a pump casing made of cast steel instead! :) To prevent accidents from happening again, it’s a good idea to choose a manufacturer of higher quality! :)

Cracks or holes are defects in the pump itself; these can be repaired by grinding them until new surfaces are created. If there is no cast iron welding rod available, try using a stainless steel welding rod instead.

Riveting can be used for small holes. Old blacksmiths can all do it.

The main reasons for the appearance of holes and cracks are likely casting quality issues; cast iron welding rods can be used for repairs, while other welding rods will not work.

Cracks in the pump casing are usually caused by casting defects, resulting from poor sand casting techniques used by the pump manufacturers during production. Since the pump casing is cast, it can be welded to repair leaks, but welding cast parts is a difficult and unreliable process. Therefore, welding repairs are only temporary solutions that can provide relief for a short period of time; their lifespan is limited, so ultimately the pump casing still needs to be replaced.

You can also try using a sealant; there are both imported and domestic options available that are resistant to high temperatures. Again, it’s necessary to sand the surface before applying the sealant. This method is relatively fast and safe to use.

Cracks or holes in the pump body are usually caused by defects in the material of the pump itself. For the problematic areas of the pump body, they can be temporarily fixed by patch welding. Weld with stainless steel electrodes for both internal and external use, and grind the interior to ensure a smooth surface. This can only be a temporary remedy; from a safety perspective, it is recommended to replace it promptly.

This is a quality issue with the pump; cast iron is difficult to weld. Perhaps one could consider using materials like rapid-hardening steel to fix the leak, but it’s still best to replace it with a pump of better quality

Cracks or holes are all quality issues of the pump itself, specifically arising during casting. Its welding requires cast iron electrodes, and these must match the composition of the materials used in casting.

Cracks or holes are quality issues inherent in the pump itself, caused precisely during the casting process. Welding it requires cast iron welding rods that match the composition of the materials used in casting. However, this is only a temporary solution; from a long-term and safety perspective, it is advisable to replace the pump as soon as possible.

What LZ mentioned is likely a quality issue with the pump, specifically defects in the casting of the casing. The term “small hole” mentioned here should refer to “sand hole” or “shrinkage cavity”” ； As for the “crack,” it’s unclear what it looks like – whether its edges are smooth or newly formed. Recommended solution: 1. Welding. Use cast iron welding rods, heat before welding, and maintain heat after welding ； 2. It is also possible to clean it first and then fill it with epoxy resin; the filler for the epoxy resin can be cast iron powder ； 3. Whether it is welding or filling, a hydrostatic test should be conducted after the treatment is completed ； 4. For newly formed cracks, drill holes at both ends of each crack before treating it to prevent further elongation.

Welding cast iron is quite difficult; it is recommended to use a pump casing made of cast steel instead!

The issue is most likely due to problems with the pump’s structure; it is recommended to contact the pump manufacturer for on-site verification； It is also recommended to replace the pump with a new one based on its usage, and to consider choosing different materials. :victory:

Our factory also uses oil pumps and hot water pumps, and we’ve never encountered this issue; it’s likely a problem with the quality of the pumps.

If the crack is severe, it is best to replace the pump; small holes can be riveted together, and it is advisable to apply glue as well. An introduction to one of the cast iron welding electrodes: Z208 cast iron welding electrode meets the GB EZC standards and is equivalent to AWS EC1. Description: Z208 is a cast iron electric welding electrode with a low-carbon steel core and a strongly graphitized flux; the weld metal turns into gray cast iron when cooled slowly, resulting in poor crack resistance. It can be used for both AC and DC, and is inexpensive. Use: Used to weld and repair defects in gray cast iron. Precautions: 1. The welding rod must be baked at around 150°C for 1 hour before welding. 2. This welding rod is not suitable for important casting structures that are subject to stress and impact. 3. Defects in areas of small, thin-walled castings that do not have high stiffness can be repaired by welding without preheating; whereas ordinary welded parts need to be preheated to 400°C, and after welding they should be kept at that temperature for slow cooling, so that the repaired area can potentially be machined.

Our factory has faced a similar situation; at first we used welding, but after some time leaks started to occur again. Later, we switched to using putty for repairs

Use welding rods specifically designed for cast iron. Wash it clean, and you can also apply some silicone