Question 1

What regulatory requirements may apply to natural gas odorization?

Accepted Answer

Federal applicability depends on the pipeline’s classification, location, service, and any applicable exceptions. Under 49 CFR 192.625(a), combustible gas in a distribution line must contain a natural odorant or be odorized so that the gas is readily detectable by a person with a normal sense of smell when the gas concentration in air reaches one-fifth of the lower explosive limit.

Paragraph 192.625(b) addresses certain transmission lines in Class 3 and Class 4 locations and includes specific exceptions. Paragraph 192.625(e) requires odorization equipment to introduce odorant without wide variations. Paragraph 192.625(f) requires periodic sampling using an instrument capable of determining the percentage of gas in air at which the odor becomes readily detectable; it also provides a separate compliance method for master-meter systems.

State requirements for intrastate facilities may be more stringent. Each operator should determine the requirements applicable to its system, jurisdiction, procedures, and operating conditions.

Burgess Pipeline Services can support field measurements, operating records, and project documentation. BPS provides operational support and documentation, not legal advice, and does not guarantee regulatory compliance.

Question 2

What are the Different Types of Natural Gas Odorants?

Accepted Answer

Natural gas is odorized through a variety of mercaptan blends: tertiary butyl mercaptan, tetrahydrothiophene, isopropyl mercaptan, dimethyl sulfide, and methyl ethyl sulfide.

Common suppliers of odorant are Arkema's Spotleak blends and Chevron Phillips Scentinel gas odorants.

Question 3

How to overcome Odor Fade?

Accepted Answer

Odor fade can be overcome by pickling, conditioning, pre-odorization, or odor fade remediation of the natural gas pipeline. Burgess Pipeline Services uses two methods to overcome the odor fade phenomenon by Static Pickling or Dynamic Pickling.

Question 4

How Much Odorant Should Be Injected?

Accepted Answer

Natural gas should be odorized so that gas is readily detectable by a person with a normal sense of smell at a concentration in air of one-fifth of the lower explosive limit. A combination of tests can be used to determine the concentration needed for injection. These test include sniff tests, sulfur analyzers or gas detector tubes.

Question 5

What is 49 CFR 192.625 Odorization of Gas?

Accepted Answer

§ 192.625 Odorization of gas.
(a) A combustible gas in a distribution line must contain a natural odorant or be odorized so that at a concentration in air of one-fifth of the lower explosive limit, the gas is readily detectable by a person with a normal sense of smell.

(b) After December 31, 1976, a combustible gas in a transmission line in a Class 3 or Class 4 location must comply with the requirements of paragraph (a) of this section unless:

(1) At least 50 percent of the length of the line downstream from that location is in a Class 1 or Class 2 location;

(2) The line transports gas to any of the following facilities which received gas without an odorant from that line before May 5, 1975;

(i) An underground storage field;

(ii) A gas processing plant;

(iii) A gas dehydration plant; or

(iv) An industrial plant using gas in a process where the presence of an odorant:

(A) Makes the end product unfit for the purpose for which it is intended;

(B) Reduces the activity of a catalyst; or

(C) Reduces the percentage completion of a chemical reaction;

(3) In the case of a lateral line which transports gas to a distribution center, at least 50 percent of the length of that line is in a Class 1 or Class 2 location; or

(4) The combustible gas is hydrogen intended for use as a feedstock in a manufacturing process.

(c) In the concentrations in which it is used, the odorant in combustible gases must comply with the following:

(1) The odorant may not be deleterious to persons, materials, or pipe.

(2) The products of combustion from the odorant may not be toxic when breathed nor may they be corrosive or harmful to those materials to which the products of combustion will be exposed.

(d) The odorant may not be soluble in water to an extent greater than 2.5 parts to 100 parts by weight.

(e) Equipment for odorization must introduce the odorant without wide variations in the level of odorant.

(f) To assure the proper concentration of odorant in accordance with this section, each operator must conduct periodic sampling of combustible gases using an instrument capable of determining the percentage of gas in air at which the odor becomes readily detectable. Operators of master meter systems may comply with this requirement by -

(1) Receiving written verification from their gas source that the gas has the proper concentration of odorant; and

(2) Conducting periodic “sniff” tests at the extremities of the system to confirm that the gas contains odorant.

[35 FR 13257, Aug. 19, 1970]

Question 6

How Often Should Pipeline Odorant Levels be Tested?

Accepted Answer

Federal regulations require periodic sampling to ensure proper odorant concentration. Testing frequency varies by system type and location, but typically ranges from monthly to annually. Methods include sniff tests and analyzers. Regular monitoring ensures compliance with safety regulations and maintains effective leak detection capability.

Question 7

What is a Mercaptan Injection System and How Does it Work?

Accepted Answer

A mercaptan injection system is specialized equipment used for natural gas odorization that precisely controls the injection of mercaptan odorant into gas pipelines. The system typically includes injection pumps, flow meters, and control valves that ensure accurate mercaptan injection rates according to 49 CFR 192.625 compliance standards. These systems are essential for pipeline odorization services as they maintain consistent odorant levels for effective gas leak detection. Burgess Pipeline Services provides comprehensive mercaptan injection system installation, calibration, and maintenance to ensure optimal natural gas pipeline safety.

Question 8

Which odorization rules should you follow for a natural gas pipeline?

Accepted Answer

You should follow federal odorization requirements under 49 CFR §192.625. In general, your gas must be odorized so it is readily detectable at 1/5 of the lower explosive limit. Depending on your system and location, state or local rules may add more requirements. We help you review the application and choose an odorization approach that supports safe, reliable compliance.

Question 9

How Does Gas Leak Detection Odorization Work?

Accepted Answer

Natural gas is naturally odorless, so operators add a distinct odorant (commonly a mercaptan blend) to the gas stream so a leak becomes detectable by smell before it reaches a hazardous concentration. Under 49 CFR 192.625, gas must be odorized so it's detectable by a person with a normal sense of smell at no greater than one-fifth of the lower explosive limit — giving operators, customers, and first responders an early warning that doesn't depend on electronic equipment.

Question 10

What Pipeline Safety Standards Apply to Natural Gas Odorization Systems?

Accepted Answer

The primary federal standard is 49 CFR 192.625, which governs odorization requirements for transmission and distribution lines, along with related recordkeeping and testing requirements under 49 CFR Part 192. State and local pipeline safety regulations may add further requirements. Burgess Pipeline Services designs and documents odorization systems to meet all applicable federal, state, and local standards.

Question 11

How Often Should Natural Gas Odorant Monitoring Be Performed?

Accepted Answer

Monitoring covers more than periodic concentration testing — it includes routine calibration and function checks of injection equipment, verification that odorant levels remain within range at points along the pipeline (not just at the injection site), and recordkeeping to document each check. While odorant concentration testing (see above) is typically performed monthly to annually depending on system type, equipment calibration and inspection schedules are set by the operator's odorization plan in line with 49 CFR 192.625 recordkeeping requirements.

Question 12

What is Pre-Odorization of Pipelines and When is it Required?

Accepted Answer

Pre-odorization introduces odorant into a pipeline before it enters full service, so gas is detectable by smell from day one rather than after odor fade has already occurred. It's typically required for new pipeline commissioning, major modifications, or when converting a previously un-odorized line to serve odorant-requiring end users. Burgess Pipeline Services coordinates pre-odorization alongside pickling and conditioning to meet 49 CFR 192.625 from the start of service.

Frequently asked questions