June 13, 2014 Roberto Morales US Environmental Protection Agency Office of Air Quality Planning and Standards Mail Code: C404-02 109 T.W. Alexander Drive Research Triangle Park, NC 27711 Re: Williams Response and Comments
to Methane

I VOC Emissions and Mitigation Techniques

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."· Report for Oil and Natural Gas Sector Compressors, Review Panel, April 2014 U.S EPA Office of Air Quality Planning and Standards (OAQPS) Dear Mr. Morales: The Williams Companies (Williams)

is submitting this correspondence

to the U.S. Environmental Protection Agency (EPA) regarding methane and volatile organic compound emissions and mitigation techniques for compressors

in EPA's, Report for Oil and Natural Gas Sector Compressors/ Review Panel/ April2014. In April, 2014, EPA solicited technical comments and additional information from reviewers on five white papers covering methane and volatile organic compounds (VOCs) emissions from compressors, hydraulically-fractured wells, leaks, liquids unloading, and pneumatic devices. Williams' response for compressors

is presented

in this letter;

a separate letter has been submitted
to EPA for pneumatic devices. Williams reports greenhouse gas (GHG) emissions for 60 natural gas transmission,

48 gathering,
16 natural gas processing,

1 petrochemical, and 2 underground storage facilities across the United States. These, and other smaller Williams' facilities that are currently below reporting thresholds, could be .impacted
by future EPA rulemaking
on methane and VOC reductions. Williams has demonstrated, and continues
to demonstrate,

its commitment and cooperation toward reducing greenhouse gas (GHG) emissions
by identifying and prioritizing GHG sources, implementing GHG monitoring programs, and working with industry groups such as Interstate Natural Gas Association

of America (INGAA), Gas Processors Association, and the American Petroleum Institute (API). Williams recognizes the importance
of this issue and shares EPA and the Administration's intention
to reduce these emissions.

In order for that effort to achieve our mutual objectives,

a strong, science-based approach must be applied

1and sufficient and accurate data must be assembled. Sufficient data does not yet exist and therefore

it would be premature for EPA to rely on existing data in any formal rulemaking proceeding.

In order to obtain sufficient and accurate data, Williams

is participating

in current studies to determine methane emissions from our systems,

is engaged
in roundtable discussions with the Secretary
of Energy and others, and commits to participating throughout EPA's proceedings
on this issue. Responses
to EPA's charge questions from Williams' subject matter experts on compressors are presented

in Section

I below. Additional comments from Williams' experts regarding the content of the EPA report are presented

in Section

II. I. WILLIAMS RESPONSE TO EPA CHARGE QUESTIONS Question

1: Please comment on the national estimates
of methane emission factors for vented compressor emissions presented

in this paper. Please comment on the activity data and the methodologies used for calculating emission factors presented

in this paper. Answer: Reciprocating and Centrifugal Compressors Williams believes the various national estimates
of methane emission factors for compressors are improving with time as reporters and researchers gain more experience

in data collection, instrumentation,
and monitoring. Williams encourages EPA and others to incorporate actual wet seal measurements,
rod packing measurements, blowdown vent measurements,
and operation-mode hours into emission factors for reciprocating and centrifugal compressors. This data is being collected on an annual basis by owneroperators and is reported

in EPA's annual Greenhouse Gas Reporting Program (GHGRP}. Question

2: Did this paper appropriately characterize the different studies and data sources that quantify vented emissions from compressors

in the oil and gas sector? Answer: Reciprocating and Centrifugal Compressors Based on Williams review,

it appears that EPA has accurately summarized methane emission factors from the referenced previous studies.

It would be helpful

if EPA would provide

a summary table of emission factors from the studies, expressed

in common units, so that readers could compare results. Question

3: Did this paper capture the full range of technologies available
to reduce vented emissions from reciprocating compressors and wet seal centrifugal compressors

at oil and gas facilities?

In particular, are there other options for reducing emissions
at existing reciprocating

or centrifugal compressors?
For 2example, the EPA is aware of "low emissions packing" for reciprocating compressors but has no detailed information
on this technology. Answer: Reciprocating Compressors At this time, Williams

is not aware of emissions-reducing technologies
for reciprocating compressors other than the ones cited by EPA in the white paper. With respect to the low emissions packing systems referred to by EPA in its question, this technology has been in existence for some time and information is available from numerous low emissions packing system manufacturers. Low emissions packing (LEP) systems employ advanced materials
of construction, un-segmented rings, tighter tolerances and smoother packing cup surfaces

in an effort to achieve lower methane and VOC emissions. Williams has conducted limited testing on LEP systems with mixed results. The primary disadvantage

of LEP systems

is they can only be installed when the piston rod is removed from the compressor. Rod removal

is infrequent, generally occurring during major compressor overhauls. For this reason, worn rod-packing rings would likely be replaced with conventional
rod packing rings and not LEP systems during most rod-packing change-outs. When major compressor overhauls are performed, use of LEP systems could be evaluated. Centrifugal Compressors At this time, Williams

is not aware of emissions-reducing technologies for wet seal centrifugal compressors other than the ones cited by EPA. Question

4: Did this paper appropriately characterize the emissions reductions achievable from the emissions mitigation technologies discussed for reduction
of vented emissions from reciprocating compressors and wet seal compressors? Answer: Centrifugal Compressors and Reciprocating Compressors Williams believes that EPA's estimated emissions from centrifugal and reciprocating compressors
are too high.
If we are correct, achievable emissions reductions, and their associated cost savings, are overestimated. Also, in Table 4-4 under Transmission

I Storage, annual natural gas savings

is reported by EPA as "zero". For purposes
of the evaluation, cost savings should not be dependent
on who owns the gas. If so, "zero" natural gas savings could be purported
at some processing plants where the gas is owned by the producer and the processor charges the producer

a processing fee. Question

5: Did this paper appropriately characterize the capital and operating costs for the technologies discussed for reduction
of vented emissions from reciprocating compressors and wet seal compressors?

3Answer: Reciprocating Compressors Rod Packing Replacement Cost Based on Williams' experience, cost estimates
by Natural Gas STAR, the TSD for Subpart 0000 Rulemaking, and ICF International

to replace rod packing systems

in reciprocating compressors

is underestimated.

In Section 4.1.3, EPA cited
a cost of $1,620 per cylinder according
to a Natural Gas STAR Lessons Learned document published

in 2006. Based on this cost, ICF International estimated

a replacement cost of $4,050 and $5,346 per compressor for Processing and Transmission, respectively. For good packing with low leak rates, the current cost for Williams

is approximately $2,300

I cylinder for materials and $500

I cylinder for labor. Most compressors have at least four cylinders,
so the estimated cost is approximately $11,200 (or more) per compressor. This cost excludes the cost of the blow-down gas and start-up purge gas associated with the rod packing replacement. Piping to a Vapor Recovery Unit The cost of $2,000 given in Section 4.2.3 for planning and installing additional piping from
a reciprocating compressor

to an existing vapor recovery unit (VRU)
is underestimated. Depending
on the proximity
of the compressor

to the VRU, Williams estimates that the cost of design and drawings, materials, labor, and required weld x-rays, would be at least $7,500 for an ({average installation". Centrifugal Compressors Section 4.3: Dry Seals The differential capital cost between dry gas and wet seal configurations

on new compressors appears to be reasonable. The capital cost for replacing wet seals with dry seals also appears reasonable. The actual replacement cost will vary greatly with compressor model. Operating cost savings are questionable

as the differential gas leakage rates presented

in Table 4-3 do not align well with Williams' experience. Williams' wet seal compressors typically are configured with gas recovery to process suction, and observed leakage rates for this configuration
are generally lower than reported

in this paper.
A second analysis by EPA to evaluate conversion from wet seal with gas recovery to dry seal is warranted. Also, in Table 4-4 the value of natural gas savings should not be reported as$ 0 for transmission/storage applications just because the operator does not own the gas. The worth of the gas should be reflected

in the table. Section 4.4: Wet Seals to Flare As noted previously, the described configuration with no gas recovery to process suction

is highly unusual
in Williams' experience. Therefore,

it is not possible to comment on leakage rate reductions.

4Section 4.5: Wet Seals Gas Recovery As noted previously, the described configuration with no gas recovery to process suction

is highly unusual

in Williams' experience. Therefore,

it is not possible to comment on leakage rate reductions. Question

6: If there are emissions mitigation options for reciprocating and centrifugal compressors that were not discussed

in this paper, please comment on the pros and cons of those options. Please discuss the efficacy, cost and feasibility for both new and existing compressors. Answer: Reciprocating Compressors Monitoring Program for Rod Packing Replacement Any future EPA regulations
on rod packing replacement for existing reciprocating compressors (i.e. installed before the Quad
0 effective date of February 15, 2012) should be based on a monitoring program, and not on a mandatory periodic replacement schedule. Williams employs

a dynamic compressor cylinder analysis on a quarterly schedule
to analyze performance which identifies rod packing leakage. The following operations, monitoring, and maintenance-related practices are suggested
by Williams
as effective emissions mitigation options for reciprocating compressors. Lubrication
of Packing

I Packing Material Proper selection of the lubricant oil, and routine monitoring
of the lubrication rate will help mitigate methane and VOC emissions

in the rod packing case. Proper lubrication

is required to effect
a good seal between the packing material and piston rod. Good lubrication also prevents overheating

of the piston rod and associated (premature) wear of the rod packing material. Lube rate monitoring

is done proactively
by Williams using electronic equipment. Piston Rod Coatings EPA notes in Section 4.1.2 that "Compressor rods can also be coated with chrome or tungsten carbide to reduce wear and extend the life of the piston rod." Williams does not support the use of rod coatings because the coatings prevent the detection
of cracks
in the piston rod which
is critical to ensuring safe operation
of the compressor. Piston Rod Smoothness Monitoring
of piston rod smoothness

is an effective mitigation measure against methane emissions.

If the rod is too smooth, the lubricant does not stick to the rod; if the rod is too rough, the packing wears out. Inspection and testing of the rod smoothness (RA) can be conducted during major maintenance events when the rod is removed. Compressor Block Valve Packing Replacement Annual monitoring and replacement

of compressor blowdown and isolation block valve packing glands {when warranted)

is an effective emissions methane mitigation measure. At facilities subject to Subpart W of the federal Greenhouse Gas Reporting Rule, emissions from compressor blowdown vents are monitored annually during the equipment leak and compressor monitoring survey.

5Centrifugal Compressors Williams

isnotawareofemissions mitigation optionsfor centrifugal compressorsotherthantheones cited byEPAinthis paper. Question

7: Aretheretechnicallimitationsthatmakethe replacement

ofwetsealswith dryseals impractical

at certain existing centrifugal compressors. Answer: Yes; dry gasseal replacement

isnotofferedonsomeoldermodelsof centrifugal compressorsdueto technicallimitations. Question

8: Aretheretechnicalreasonswhyanoperatorwoulduseawetseal centrifugal compressorwithout

agas recoverysystem? Answer: Williams

isnotawareof anytechnicalreasonswhyitwouldnotbe possibletouseagasrecoverysystem onawetseal compressor. Question

9: Aretheretechnicallimitationsthatmaketheinstallation
of gascapture systems
atcertain reciprocating compressorsimpractical? Answer: No. However,thecostof installing

avaporrecoveryunit (or flare)whereonedoesnotexist (e.g.ata compressorstation)

isacontrolcostthatshouldbeevaluated
byEPAaspartofits analysiswhen evaluatingthe rangeof optionsfor cost-effectively reducingmethaneemissions.Theinstallation
of VRUsorflaresatsmaller compressorstations maybecost prohibitive

atsmallerfacilities. Question10: Pleasecommentonthe prevalence
ofthedifferentemission mitigation options
inthefield. Answer: Reciprocating Compressors Replacement

ofrod packingand replacement

ofblowdownventvalve packingareprevalent

inthefield andareviable,realistic optionsfor reducingmethaneemissionsfrom reciprocating compressors.Vapor recoveryof reciprocating compressoremissions

is prevalentwherethereareVRUsorflares.Mostolder compressorstationsdonothave VRUs,thermaloxidizersorflares;theirinstallation

ismoreprevalent
at newercompressorstations. Vapor recoveryand flaring (combustion)

ofrod packing emissions,

6blowdown vent valve emissions, and blow downs,

is more prevalent
at processing plants than at compressorstations. Centrifugal Compressors The useof dry gasseal centrifugal compressors

is nowan industry-standard

for centrifugal compressors asameansof reducing methane and VOC emissions and is a practice that Williams follows.

In fact, Question 11: Given the substantial benefits of dry seal systems (e.g., lower emissions, less maintenance, and higher efficiency), are youawareof situations where newwetseal centrifugal compressorsare being installed in the field?
If so,arethere specific applications that require wetseal compressors? Answer: No. Williams no longer installs wetseal centrifugal compressors. II. ADDITIONAL WILLIAMS COMMENTS Williams offers the following additional comments for EPA's consideration regarding the technical content of the compressorwhite paper.Williams' intent

is to provide useful information that will: {1) help EPA's understanding

of compressor operations; and {2) allow EPA tomore fully evaluate the range of options for cost-effectively cutting methane emissions. Reciprocating Compressors 1. Page 3, Third Paragraph Suggest the following revision (in italics) when defining

a reciprocating compressor: A piece of equipment that increases the pressureof a process gas by positive displacement, converting rotational motion ofthe crankshaft

tolinear motion of oneormorecylinder pistons. 2. Page 4,1st Paragraph under Section 2.1 Recommend the following addition when describing the operation
of a reciprocating compressors (in italics): In a reciprocating compressor,natural gasenters the suction manifold, and then flows into a compression cylinder where
it is compressed
by a piston driven in a reciprocating motion by the crankshaft powered by aninternal combustion engineorelectric motor. 3. Page 4, Last Paragraph Suggest the following modification

(in italics) with respect torod packing leakage: Over the operating life of the compressor,the rings become wornand the packing will begin to wear resulting

in higher leak rates.Emissions from packing systems originate from one component/ the packing case.Leaks mayoccurbetween the packing caseand nosegasket/ and from the seal ringsand packing cupsinside the packing case.Typically/ gasesleaked from the packing casearevented orflared.

74. Page 5, Figure 2-1 In future documents,

it would be helpful toshow the location of the nose gasket onthe right-hand side of the packing cup,between the packing cupand the cylinder head.

It would also be beneficial tothe show the common paths of natural gas leakage

in the figure. 5. Page 9, Last Paragraph Williams

is not familiar with the fuel saver system referenced
by EPA (below
in italics) that would result in anidle, partially pressurized compressor. Different emission rates werecalculated for the different operating modes of the compressor (GRI/EPA, 1996bL and wereas follows; • Operating and pressurized; •Idle and fully pressurized; •Idle and partially pressurized using
afuel saver system (reciprocating compressors only); •Idle and depressurized. 6. Page 31, First Paragraph In the last sentence, EPA assumed 11.5 cubic feet perhour per cylinder for newly installed rod packing for cost development purposes.Williams believes this is high. According
to Ariel,
a manufacturer

of rod packing, leak ratesfor newrod packing rangebetween

6 and 12 scfm. Centrifugal Compressors 1. General Comment
#1 It seemsthat the white paper only considers field measurements
for dry gasseal vent flows and not design values from the seal vendors. Future consideration

of design values would be useful. 2. General Comment
#2 Data werenot presented

in consistent units throughout the report; reporting units weredifferent

in virtually everytable. 3. General Comment
#3 It maybe useful to normalize methane emissions data by compressor capacity and evaluate the results. Centrifugal compressorsareoften larger than reciprocating compressors. Failing to normalize the data by equipment capacity ignores the effect of larger natural gasvolumes handled by larger compressors. 4. General Comment
#4

8It maybe useful to normalize methane emissions data by suction process gas pressure. Dry gasseal leak rates vary greatly with pressure.Wet seal system gasentrainment also varies with pressure. 5. Page
5 Wet seal systems arenot adequately described

in the white paper.EPA should clearly indicate for the wetseal data collected whether absorbed gasis vented to atmosphere,

or partially recovered
to compressorsuction. The latter
is far and awaythe most common (possibly only} configuration

in Williams' fleet. This makes

a great difference

in leakage rate. 6. Page 7, Figure 2-3 This depiction
of a dry seal is significantly different than the typical configuration

onWilliams' fleet of centrifugal compressors (mostly Solar and Dresser Rand}. Figure 1.C-8 (shown below} from API 617 is more representative. The important difference

is that natural gasis expected only from the "Primary seal gas leakage" path, and notthe "Secondary seal gas leakage" path. The "Separation gas" is usually air (sometimes nitrogen} and this leaks from the secondary vent. The natural gason the inboard side of the secondary seal is at atmospheric pressure,
soflow of natural gasacrossthis seal is extremely low. Process Side 7. Page 14, Third Bullet: Primary seal gas suppty Inner Ia by Primary seal gas leak.age Secondary seal gas leakage Primary sea!Secondary **back~up** seal Separahon seal 1.C-8- Tandem Gas Seal Bearing Side

9"For centrifugal compressors equipped with wet seals, measurements weremade atthe wetseal degassing fill porttothe seal oil pump using plastic bags of known internal volume and measuring the required flow tofill the bag." Williams

is not familiar with the configuration described. Specifically,
onmorethan SO wetseal centrifugal compressors operated, nonehave
afill portonthe degassing system. Williams recommends that, when possible, future measurement studies conducted
by researchers measure emissions
atthe openend of the wetseal degassing tank vent stack. 8. Page 36, Third Bullet: Power consumption
for wetseal pumpsvaries with compressor size, but the SO -100 kW cited by EPA in the white paperseems unusually large. For reference,

a20 hp (1S kW) pump
is adequate for typical Solar Turbine compressors

in the S,OOO- 10,000 hp size. Williams believes that EPA's consideration

of the above responseand comments, and input from others in the natural gas industry, will help the Agency better understand options for cost-effectively reducing methane emissions. We believe that somedata gapsstill remain, and that filling these gapswith additional measurement data is necessarybefore EPA develops best practices, voluntary actions, and

I or regulations regarding methane reductions. Williams appreciates the opportunity

to provide comments regarding EPA's Report for Oil and Natural Gas Sector Compressors/ Review Panel/ April2014. Should youhave questions regarding these comments, please contact meat (713) 21S-2134
orat glen

.jasek@williams

.com

. Sincerely, Glen Jasel The Williams Companies, Inc. Director of Environmental Services

10