Understanding Copper Tube

pressure-temperature ratings of

 Brief History on Press Fittings

Back in the late 1950’s, press fittings were first patented in Europe; but nearly 40 years later, press fitting began to make a name for themselves in the United States. Press fittings were designed to be cost-effective, quick, secure, and easy to handle. With less emphasis on skilled labor, companies could utilize existing personnel to install press fittings which would save on costs, but time was also saved because of the tools used to ensure a quick installation versus other methodologies such as soldering or brazing. Companies could also save time because no open flame is needed therefor no burn permit is required. To learn more about the many benefits and features of Press Fittings, please click here.


Copper Tube

Merit’s line of Copper Press Fittings mate with Copper Tubing using Copper Tube Size (CTS). There are many benefits as to why contractors utilize Copper Tube in plumbing, heating, and cooling installations, and listed below are just some of the many benefits:

  • Ease of installation results in time savings, less material being used, and a performance that is long-term & reliable
  • Easier to transport since it is lightweight and takes up less space
  • It’s a very malleable and can be bent and formed
  • Easy to join and safe
  • Possesses excellent corrosion resistance, high mechanical strength, high temperature resistance and lifetime resistance to UV degradation
  • Assures trouble-free service
  • Recyclable


Copper plumbing tube starts with copper (raw material) which may be either copper scrap, newly refined copper (called cathode copper, or cathode) or copper ingots. The manufacture of copper plumbing tube depends on cost, availability, and the furnace capabilities. Below are some ways in which copper is manufactured:

  • Copper wire is recycled after it is stripped of its insulation resulting in copper scrap. The copper scrap is relatively clean, but it does contain some impurities. These include zinc, tin, nickel, and some iron. However, only the highest quality grades of scrap are used to manufacture this type of tube.
  • Cathode copper is manufactured in large electrolytic cells that refine impure blister copper taken from smelting and refining furnaces. Cathode copper is one of the purest metals.
  • Copper ingot is mainly used by tube mills and bears a resemblance to large bricks cast from re-melted cathode or refined scrap.


How do you know which type of copper tube to use? There are several factors to consider for a particular application that have proven successful:

  • StrengthCopperPress Fittings
  • Formability
  • Mechanical Factors
  • Plumbing & Mechanical Codes


Traditionally, Merit’s copper press fittings are used with Type L copper tube.

Copper’s excellent malleability & it’s strength when cold worked are advantages for press fitting connections. There are pressure temperature ranges for press fittings (no flame joints) listed below. Prior to connecting, be sure to follow protocols for tubing inspection and readiness to connect.

Copper.org's Pressure-Temperature Ratings of No-Flame Joints

                                                                        Page 67, Copper.org’s Copper Tube Handbook

                            Copper.org's Dimensions & Physical Characteristics of Copper Tube:  Type L

                                                                                  Page 67, Copper.org’s Copper Tube Handbook

Resources:      https://www.copper.org/publications/newsletters/innovations/1998/09/howdo_tube.html   https://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf                      Merit Brass Company

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