Over the past few years WG’s suppliers have changed the way that they operate their pipelines. This has caused us to begin receiving odorized gas from our suppliers for the first time. This gas being odorized is not guaranteed and the levels of odorization can constantly change in a short period of time. This presentation will discuss the following.


To alert in cases of leakage, liquid propane gas (LPG) is usually odorized with mercaptan additives such as ethyl-mercaptan, tert-butyl mercaptan (TBM) and dimethyl sulfide (DMS). Continuous monitoring is required to ensure the effectiveness of the odorization process. However, this is a real challenge because of the complexity of the gas matrix. Moreover, the odorized liquid vapors may not be uniform due to the different boiling points of the species.

The energyMEDOR analyzer is a well-known solution for sulfur-based odorants monitoring in natural gas in the USA. It is compliant with ASTM D7493-14 standard. It allows the rapid and accurate analysis of H2S, mercaptans, dimethyl sulfide (DMS) and/or total sulfur (TS) in gas. It consists of an automatic process gas chromatograph equipped with a sulfur-specific electrochemical wet cell detector (auto-GC-ED) which only reacts with sulfur compounds without interferences and provides excellent linearity at ppb or ppm or even at low % concentrations.

When associated with a dedicated sampling system developed by Chromatotec, representative liquid samples are extracted directly from the LPG matrix.

The system is available with dedicated configuration for safe and hazardous areas (ATEX, IECEx, CSA and CSA international certifications) including an integrated N2 generator. Its simplicity for online application in refineries and petrochemical plants is achieved thanks to its flameless detector. Nitrogen is used as the carrier gas: no hydrogen is required.

This reliable, simple and robust turnkey solution is fully autonomous thanks to the integrated gas generators to avoid the need for gas cylinders and embedded internal calibration for automatic data validation. Moreover, this process device is designed for very low maintenance requirements.

Odor intensity monitoring has been performed for several decades now but the tools, methods, knowledge base and overall odorization program has and will continue to further develop as the combustible gas industry continues advancing its successful goals of public and personnel safety, minimizing liability and complying to federal DOT code 49 CFR 192.625 and respective state regulations.
The paper will focus on odorization history, compliance to federal DOT code 49 CFR 192.625, odor intensity monitoring tools and monitoring methodology.

Natural gas is odorized for safety reasons. In France, the number of RNG (biogas) injection points increase continuously to reach almost 100 points at the end of 2019. It was decided to follow the same standards to odorize RNG as the one applied for natural gas. THT is used as gas odorant. However, technical issues need to be faced to inject and control the odorization of RNG. One of the reasons is that RNG injection into the network is not continuous. The other reason is the fact that the flow rate of RNG injected could be very small (below 40 Sm3/h).

In this presentation, RICE (R&D lab of GRTgaz, the main transmission company in France) also presents its last research on odorization of RNG.

The presentation covers basic questions of non-conventional gas odorization including:

It will also feature discussions of:

Closed Loop Control
Precise dosing, metering and control of the odorant in the gas. Here we will describe how the combination of pump-flow meter-controller helps to save odorant and money.
Reference examples of delivered systems
Here we would like to present the systems that we have delivered in the past: from the smallest odorizing systems done according standard requirements up to the most sophisticated skids designed and manufactured according complicated oil and gas specification and difficult local requirements.

The paper presents an overview of natural gas odorization as a safety standard for detection of gas leakage. Different odorant choices with advantages and disadvantages are discussed. Following the course of the supply chain of natural gas, the present status of gas odorization for NGV (natural gas vehicles), and in particular CNG (compressed natural gas, is detailed. Different options on where and how to odorize LNG (liquefied natural gas) for transport or for remote LNG storage. The paper reports the results obtained during a pilot test run involving odorization of LNG during tank-loading of an LNG fuel truck, including simulation of standard use and leakage scenarios.

Natural gas odorant spills can be very costly to the utility, put the public at risk and can cause major business disruptions. Building a robust odorization system considering odorant spill prevention and odorant spill risk mitigation can greatly reduce these risks. The direct cleanup costs for a small odorant spill can easily reach 6 figures with larger spills reaching 7 figures. With good engineering, proper planning, proper assessments odorant spills can be greatly reduced and these steps can greatly reduce the impact of an odorant spill were one to occur.

In-Service Pipeline Conditioning requires the diligent monitoring of odorant concentrations in the pipeline while it is being conditioned. This paper presents the utilization of portable electronic monitoring equipment to provide companies with the ability to remotely monitor and record odorant concentration, pressure, temperature and flowrate. The paper will present the in-service conditioning process beginning with pre-planning to the eventual decommissioning and removal of equipment. The paper will include field experience case studies and recommended adjustments based on the information received from the monitoring equipment.

In a recent community expansion project in Milverton Ontario, odorant levels faded over the course of several months. The pipeline was conditioned (pickled) before going into service. Results of that conditioning were successful, meaning that for several weeks after the conditioning, the odorization levels fell within the acceptable range.

Unfortunately, after a few months, the odorization levels fell to below acceptable values. Why did the odorant levels drop? What caused the fading? How can we ensure this does not happen again? How can we be prepared for a future project with a similar situation?

This paper will address this situation and these questions, and make some recommendations for future projects

National Grid is installing new plastic and steel gas main throughout Brooklyn, parts of Queens, and Staten Island. Odor fade is a problem, often showing up days after main is placed in service. National Grid has developed and implemented two methods to overcome this.

We pickle for several days, large diameter steel mains prior to placing in service using a portable odorant injection trailer which we designed for the streets of New York City.

Direct odorant injection into plastic main is not acceptable at National Grid and short lengths of steel main require minimal amounts of odorant, making over odorization a real problem. We have designed and implemented a simple portable odorant wicking and monitoring system which has proven to be reliable, safe and easily adapted to various scenarios in NYC. Our presentation will focus on this process and will review projects it was used on.

Pickling of new steel pipelines is a transitory event of relatively short duration (days to a few months) that carries high risk due to the fact that this task falls outside the normal operating conditions of distribution or transmission of natural gas. It is also prone to over-odorization or under-odorization because of the complex nature of the on-going reactions between rust and mercaptans inside newly installed pipe.

Techniques exist to predict volume of odorant that needs to be added to pipeline to complete the pickling process. This is done in order to reduce risk, manpower, time and costs for pipeline startups. Complex variables such as pipeline steel quality, pigging procedures, drying procedures, storage time of pipeline, exist that affect odor fade that are outside the control of the operator. The author will try to demonstrate that a consistent odorization strategy and not a fixed recipe is a safer approach to tackle startup with predictable results.

The author was involved in a testing program in 1988 where increasing gas flow rates were injected into the ground and the results measured.  The data from this testing showed that the gas flow used or created channels through which the gas traveled from the leak to other locations.  If gas travels through channels or creates fractures in the soil to facilitate flow, then the surface area to scrub odorants is substantially reduced.  Indeed, many, if not most, gas explosions are associated with someone smelling gas at some point in time.  That is evidence that odor scrub in a gas explosion scenario is less effective than previously assumed and maybe very ineffective.  This paper will explore this approach.

TBM and THT are highly effective as odorants for natural gas, being amongst the most odoriferous compounds known to man. In two different Australian pipelines where a blend of 70% THT and 30% TBM has been used for more than 25 years, laboratory results still show little or no presence of TBM, leaving THT as the only warning agent. Although the oxidation of mercaptan odorants has been recognized as an issue for many years there is little quantitative data available about the advantages of having THT as part of this blend. In this case study we show Chromatography results to demonstrate how, after 25 years, TBM has just started to be detected in the samples and still not to satisfactory regulatory levels. THT continues to have the important role of maintaining the gas safe in these two pipelines.

GTI will present data from its latest efforts in odorization research.  These include modeling the dispersion of odorant as it enters a pipeline, looking at the impact of liquid odorant on plastic and rubber materials used in pipelines, and results from a coating study with TBM and THT odorants.

Facilitators: Dave Bull, Paul Wehnert, Mark Gunsalus

Gas odor level testing programs are an important part of delivering safe and reliable natural gas. This paper will review olfactory biology basics, regulations, odor fade, program development, program execution and training. The processes have been developed and refined over 30 years to ensure proper odor levels and identify deficiencies so they can be quickly rectified.