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What are the downsides for galvanized steel pipes + press fittings vs. welded steel pipes in a heating application? Diameter would be DN25/1".

Background: The customer specifies only steel, only welded connections for heating pipes starting at this size. The contractor wants to use press fittings, presumably because this way the installation will be easier. The rooms the installation will take place are rather full.

Are there good technical reasons to avoid galvanized steel pipes + press fittings? Corrosion, longevity, others?

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  • $\begingroup$ What heating application? and what is the range of pressure and temperature inside the pipes? $\endgroup$ – Algo Nov 26 '15 at 16:29
  • $\begingroup$ Heating water, I'll have to look up (not at work now) but pressure will be around one or two bar or less and the temp range between 70-95°C. Just for orientation, I'll look the exact numbers up tomorrow $\endgroup$ – mart Nov 26 '15 at 19:32
  • $\begingroup$ Didn't find exact number for pressure. These pipes are typically PN16 so I don't see this as an issue. Am I missing something? $\endgroup$ – mart Nov 27 '15 at 8:26
  • $\begingroup$ @mart: It seem nobody has better information. Could you write an answer, so we may vote? $\endgroup$ – Adrian Maire Nov 21 '17 at 14:54
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Galvanized coatings tend to chip and flake after a while. Regardless of the coating, a plain steel pipe WILL corrode/rust after a while. Compression fittings will also eventually loosen up over time, depending on the conditions, sooner or later. Welded stainless (316 or so) while the most difficult to install, would be the most dependable setup for the long haul.

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What are the downsides for galvanized steel pipes + press fittings vs. welded steel pipes in a heating application? Diameter would be DN25/1".

Background: The customer specifies only steel, only welded connections for heating pipes starting at this size. The contractor wants to use press fittings, presumably because this way the installation will be easier. The rooms the installation will take place are rather full.

Are there good technical reasons to avoid galvanized steel pipes + press fittings? Corrosion, longevity, others?

Technical reasons: Regulations: Health and Safety Executive - Design Codes - Pipework

Corrosion, longevity: Corrosion, yes and longevity, no. If it's for galvanized hot water radiators you should be OK, but it's up to the customer and regulations. For drinking and bathing water you wouldn't want galvanized.

See these answers, people dislike galvanized - presumably so does the customer.

Answers from our sites:

Galvanized pipe life expectancy - particularly this answer and associated photo.

Are galvanised steel pipes suitable for supplying hot water?

Replacing galvanized

If the customer has spoken with an Engineer or spent a lot on drawings and inspections they may be unreceptive to changes. If it's an idea they came up with on their own they might appreciate unbiased advice - the contractor would need to be certified to weld pipe, press-fitting is easier.

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