Oil Tank Fill & Vent Piping Materials
Can I use galvanized or plastic?

Approved Oil Tank Piping Materials

Permitted Fill & Vent & Fuel Line Piping Material for Oil Storage Tanks & Oil Burners

Using the Seattle 2015 Mechanical Code Chapter 13 as a model, we can see a summary of permitted fuel oil piping materials in table form with the applicable piping standards listed below:

Notes to the table above:

1. Type M copper which has thinner walls than type K or L, may not be permitted in some jurisdictions.
2. Notice that the adopted and model mechanical codes do not mention the word "galvanized" nor "iron" - though in popular parlance some installers may refer to steel piping as "black iron" or "galvanized iron" pipe. There is no prohibition nor even use of either of those terms.
3. The practical distinction between "pipe" and "tubing" is that tubing is flexible and is commonly used in smaller sizes for fuel distribution between an oil storage tank and the oil burner.
4. Source: 2015 SEATTLE MECHANICAL CODE, CHAPTER 13, FUEL OIL PIPING AND STORAGE [PDF] retrieved 2021/10/03, original source: http://www.seattle.gov/documents/Departments/SDCI/Codes/MechanicalCode/2015SMCChapter13.pdf

Typical Mechanical Code Sources for Fuel Oil (Heating Oil) Piping Materials

Photo: this installer used iron pipe for the fill pipe and plastic for the oil tank vent pipe. Is this allowed? Maybe.

[Click to enlarge any image]

• Brass pipe (where permitted) joints
  
  shall be brazed, mechanical, or threaded - IMC 1303.4
• Brass tubing joints
  
  shall be brazed or mechanical - IMC 1303.5
• Copper or copper alloy pipe joints
  
  shall be brazed, mechanical, threaded, or welded - IMC 1303.6
• Copper or copper alloy tubing joints
  
  shall be brazed or mechanical, or flared - IMC 1303.7
• Joints between different piping materials
  
  must use approved adapter fittings, dielectric fittings, or brass converter fittings; fittings must be approved for fuel-oil piping systems and must be made tight with appropriate sealants; - IMC 1303.1.1, 1303.3
• Non-metallic piping,
  
  permitted in some jurisdictions; connections must be as per manufacturer - IMC 1303.8
• Steel pipe joints
  
  are threaded or welded; note that the model codes don't mention a distinction between black steel pipe and galvanized steel pipe for heating oil applications - IMC 1303.89
• Steel tubing joints
  
  shall be mechanical or welded - IMC 1303.10

Not-Permitted Oil Tank Piping Materials

• Cast iron fittings
  
  shall not be used - IMC 1303.1

Reader Comment: ok to use galvanized fittings on oil tank piping?

Galvanized fittings should not be used on oil pipe from tank. Which is contrary to your recommendations. - John, 2021/09/30

This comment and reply were posted originally at OIL FILL & VENT PIPING FAQs

Moderator reply: steel oil tank piping (black or galvanized "iron") and in some cases plastic (non-metallic) piping for fill and vent pipes

@John,

Thank you for the comment as your opinion contradicts typical oil tank piping codes on types of oil tank piping permitted and so led us to double-check our research on this question

Oil tanks supplying oil burners used in residential and commercial heating applications are fueled by above-ground or buried oil storage tanks whose fill and vent piping is usually steel (referred to also as black iron pipe or galvanized iron pipe); in some jurisdictions non-metallic piping is permitted, though code details will specify that any joints or connections must be made using the manufacturer's instructions.

Here is a typical oil tank piping code excerpt on the types of piping permitted at oil tanks - focusing on the fill and vent pipe where either black iron or galvanized iron are permitted along with brass and copper or steel.

Where flexible copper is used, of course, is not for the fill and vent pipe to the oil storage tank but for piping fuel between the oil storage tank and the oil burner .

Adding a few details on oil piping in Connecticut using Norwalk's code as an example

47-22 Connections and unions.

All connections shall be made perfectly tight with well-fitted joints. Unions shall be used as burners to facilitate removal. All unions, shall be of an approved type, having conically faced joint, and obviating the use of packing and gaskets.

§ 47-30 Type of pipe;

brass union required; material on pipe joints; cutoff in steam installations.

A.

All pipes used in fuel-oil heating installations shall be of standard, full-weight brass, copper, galvanized iron or steel, with suitable brass or galvanized malleable iron or steel fittings. No rubber or other packages shall be used.

If unions are used, at least one face must be of brass with close-fitting conical joints. Litharge and glycerin, shellac or other suitable material shall be used on pipe joints. Such piping shall run under the cellar wherever possible and shall be protected from injury.

using the 2015 UMC as an example, Chapter 13, Section 1303, Joints & Connections:

1303.1 Approval:

Joints and connections shall be approved and of a type approved for fuel-oil piping systems. Threaded joints and connections shall be made tight with suitable lubricant or pipe compound.

Unions requiring gaskets or packings, right or left couplings, and sweat fittings employing a solder having a melting point of less than 1,000 F (538 degC) shall not be used on oil lines. Cast iron fittings shall not be used. Joints and connections shall be tight for the pressure required by the test.

On copper oil piping lines, flare unions like the brass 3/8" flare nipple union... are common on oil piping (not underground).

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So where might John have heard advice on avoiding use of galvanized iron piping with oil fuels?

In automotive applications, not heating oil burner applications, one should not use galvanized iron piping because the additives in diesel fuel can dissolve components of the galvanized coating on pipes, sending the dissolved constituents into the automotive engine where it may foul the engine's fuel system.

In sum,

• It is proper to use black or galvanized iron pipes for the oil storage tank fill and vent pipes. Non-metallic piping is permitted in some jurisdictions.
• Do not use galvanized iron pipes in automotive engine fuel supply systems.

John, if you have another authoritative source that gives contrary information please do share it as that would be most helpful.

On 2021-10-03 by inspectapedia.com.moderator - use black or galvanized iron pipes for the oil storage tank fill and vent pipes

@John,

Thank you for the comment as your opinion contradicts typical oil tank piping codes on types of oil tank piping permitted and so led us to double-check our research on this question.

Please see your question and our complete response in the article above on this page.

On 2021-09-30 by John

Galvanized fittings should not be used on oil pipe from tank. Which is contrary to your recommendations.