GasCompressorAssociationP.O.Box167688Irving,TX75016-7688Phone:972-518-0019June16,2014OfficeofAirQualityPlanningandStandardsU.S.EnvironmentalProtectionAgencyMailCode:C404-02109T.W.AlexanderDriveResearchTrianglePark,NC27711Re:GCACommentsontheOilandNaturalGasSectorCompressorsWhitePaperToWhomitMayConcern:TheGasCompressorAssociation(GCA)isatradeorganizationforthenaturalgascompressionindustry.Ourmembercompaniesmanufactureandpackagenaturalgascompressorpackagesandrelatedcomponents.Theproductsourmembercompaniesmanufacture,sellandoftenoperateareutilizedthroughouttheoilandgasindustrytofilltheenergyneedsofournation.TheGCAwouldliketoprovidecommentsonfourmaintopicsinregardstotheOilandNaturalGasSectorCompressorsWhitePaper:1.Proactiverodpackingreplacementoncompressorsnotlocatedat wellheadsisprotectivefortheenvironmentwithoutbeingexcessivelycostprohibitive.Predominantrodpackingtechnologyhasresultedinlowerleakrates,andnewerpistonroddesignsimproveexpectedlifewithoutthenecessityforfurthermaterialspecification.Furthermore,thereshouldbeallowancesfor"lowemission"orimprovedrodpackingsthatwould havelessleakagetotheatmosphereforanextendedperiodoftime.2.ItisnotcosteffectivetorequiretheinstallationofagasrecoverysystemorVRUsolelyforthecaptureandcontrolofrodpackingemissions.Furthermore,equipmentnecessarytoroutecompressorrodpackingemissionsatafieldsitewouldresultinanincreaseinnaturalgasemissions,offsetting anyimprovementsfromsaidcaptureoftherodpackingemissions.Additionally,costsavingsfromcapturednaturalgasarenotrealizedbythecompaniesleasingandmaintainingthecompressors.3.Someofthestudies involvedincorporatefaultyormisleadingassumptionsthatdonotcorrelatewithcompressorsoperatingatremotefieldsitesintheOilandNaturalGassector.4.Thedefinitionofcentrifugalcompressorshouldbereferencedfrompreexistingregulationstoimproveclarityandconsistencybetweenrules.GCACommentsOilandNaturalGasSectorCompressorsWhitePaperJune16,2014Comment1:Proactiverodpackingreplacementoncompressorsnotlocatedatwellheadsisprotectivefortheenvironmentwithoutbeingexcessivelycostprohibitive.Predominantrodpackingtechnologyhasresultedinlowerleakrates,andnewerpistonroddesignsimproveexpectedlifewithoutthenecessityforfurthermaterialspecification.Furthermore,thereshouldbeallowancesfor"lowemission"orimprovedrodpackingsthatwouldhavelessleakagetotheatmosphereforanextendedperiodoftime.Reciprocatingcompressorrodpackingswereformallyaddressedunder40CFR60Subpart0000.Certainapplicationswereexcludedfromtherule,andtheGCAbelievesthattheseexclusionsareworthwhile,perourknowledgeoftheindustryandtheargumentspresentedinthesupportingTechnicalSupportDocuments(TSDs)referencedintheWhitePaper.Specifically,compressorslocatedatawellsiteoranadjacentwellsitearenotaffectedfacilitiesundertherule.Compressorslocatedatwellsiteshaveseveralcharactersticsthatjustifyexclusion.Thevastmajorityofleakageonacompressorrodpackingisbetweenthepackingandtherod.Compressorslocatedatwellsitestendtobesmallerthancompressorsusedinotherapplications,bothinroddiameterandthenumberofthrows(rods).Asaresult,thereislesssurfacecontactareatoleak.Forexample,atypical200horsepower3stagecompressorlocatedatawellsitewouldhavetworodsthathaveadiameterof1.25inches.Alargercompressorintransmissionservicewouldtypicallyhave4or6rodsthathaveadiameterof2"orlarger1,resultinginaleakagepaththatis3to6timesthatofthesmallercompressor.Furthermore,wellsitecompressorstendtohavelowerpressuresinthefirststagecylinder.Therefore,theleakageacrossthepackingislesswiththelowerpressuredifferential.ThewhitepaperpublishedbytheEPAreferstonewernon-metallicrodpackingmaterialssuchasTeflon®orPTFE(Polytetrafluoroethylene).Non-metallicringssuchasPTFEhavebeenthedominantrodpackingmaterialfordecades,andtheGCAestimatesthatover95%ofrodpackingsinusearealreadymadefromsuchnon-metallicmaterials.Thedesignoftherodpackings,includingthearrangementanddesignoftherings,varybymanufacturer,andtherearesomenewerdesignsthatmayhavereducedemissionsandextendedservicelife,accordingtoavailablesalesliterature.Thetechnologybehindthesenewerdesignsevolved,likemost1"Larger"asusedisconsistentwiththeEPAWhitePaperthatreferencesa1,600horsepowerthreshold.This1,600horsepowerthresholdoriginatedinthe1996EPA/GRIstudy.Page2GCA Comments Oil and Natural

Gas Sector Compressors

White Paper June

16, 2014 technology,

based

on demand

and economics

of operation.

An unintended consequence

of 40 CFR 60, Subpart 0000

has been the detrimental

effect

on technology development.

Because Subpart 0000 requires replacement

of rod packings

at 26,000 hours, regardless

of the technology employed,

there

is no incentive

to drive technological development

of improved

rod packing performance

that may have

a longer

life but with

a higher associated

cost. Thus,

it is important

for the EPA

to consider variances

in technology

and make allowances

for improved designs (both current

and future)

in any future rulemaking
effort. There were some comments

in the White Paper

on pages

30 and

32 regarding

the piston
rods themselves

and processes

such

as chroming

or coating
with tungsten carbide

to lessen

the wear

on the rod. These types

of coatings, though,

are not common,

do not necessarily improve packing sealing

and rod life, and are only necessary

in special applications. Newer piston

rod designs

and materials (without special coatings)

have improved

the expected life of piston rods, and further material specification

by

a regulatory agency

is unwarranted. Rods
are often removed

to change

the rod packing

and are subsequently inspected

for surface finish
and condition during

rod packing maintenance activities. Because there

is
a significant amount

of labor and downtime associated

with removing

the rods again

at

a later date, they
are changed

or repaired

as necessary

(due

to the long rod life expectancy

and high variability

in gas conditions)

at that time.

It would

not
be practical

to implement

a regulatory

life limit,

as

it would only result

in unnecessary expense

with little

to no benefit. There

is very little data that the GCA could find regarding

rod packing wear over the life of the rod packing, specifically

as

it relates

to increases

(if any)

of emissions

over time.
The limited amount

of data that exists

has

a great deal

of variability

in it, and much

of the data was collected

to test the performance

of specific designs relative

to each other

in

a unique circumstance.

Great caution should

be exercised

to not draw erroneous conclusions

based

on limited
data from

an extremely

small population

that was not intended

to cover

a wide range

of operating conditions.

As mentioned
above, technology

does evolve,

but the EPA should

not favor one brand

or type

of technology

to the detriment

of others
that may provide superior results

in any
of the various potential operating conditions

that could

be present

in an Oil and Gas field application. Comment

2: It
is not cost effective

to require

the installation of

a gas recovery system

or VRU solely

for the capture

and control

of rod packing emissions. Furthermore, equipment necessary

to route compressor

rod packing emissions

at

a field site would result

in an increase

in natural

gas emissions, Page

3GCACommentsOilandNaturalGasSectorCompressorsWhitePaperJune16,2014offsettinganyimprovementsfromsaidcaptureoftherodpackingemissions.Additionally,costsavingsfromcapturednaturalgasarenotrealizedbythecompaniesleasingandmaintainingthecompressors.TheEPAmentionstwomethodsofemissionsreductionforreciprocatingcompressors.ThefirstistheREMTechnology,Inc,SlipStream®system,whichisahighlyspecializedapplication,verycostly,andnotwidelyusedintheOilandNaturalGascompressionindustry.Therearesomechallengesassociatedwiththesystem,suchasthesafetyhazardofmixingairandfuelintheairinletsystemforwhichitwasnotdesignedandenginestabilityduetothevaryingBTUoftheadditionalfuelsource.Inordertoensureproperengineoperation,ahighlysophisticatedenginecontrolsystemwouldalsoberequiredtoaccountforthevariabilityofthefuelsources.Thisadditionalequipmentcreatestheneedforanadditionalexpense.TheREMsystemwillalsobedifficulttoapplytosmallerhorsepowerpackagesduetothelimitedphysicalspaceavailableonthepackage.Avastnumberofvalves,flowmeters,andfiltersarerequiredforoperation.ItshouldbenotedthattheapplicationoftheREMsystemwassubsidizedbya$2.4Milliondollargrant,andtheeconomicsincludedcreditsforreductioningreenhousegassesinAlberta,Canada.Furthermore,alloftheinstallationsweredoneon600to1000horsepowerengines.TheseeconomicsarenotrepresentativeoftheoilandgasindustryintheUnitedStates,andthelimitedhorsepowerrangeandenginetypesdoesnotproveviabilityofthisproductforwidespreaduse.Thesecond systemmentionedisaVaporRecoveryUnit(VRU).TheuseofVRUsystemstocapturerodpackingemissionsisnotcommoneitherandwouldrarelyifeverbeconsideredcosteffective.ThebiggestchallengeisthatmostoftheVRUsystemsareelectricdriven,andthemajorityofthesourcesareremotewithnoaccesstothepowergrid.ThereisanoptionforanaturalgasdrivenVRU,butthiswillnegateanygainsinemissionsreductionsbythesystem.IfaVRUisakeadyonasite,thepackingventscouldbepipedin.However,mostoftheVRUsarelocatednearstoragetankswhicharetraditionallyplacedasignificantdistanceawayfromgascompressors.Itisverypossiblethatexistingsystemswouldbeundersizedtoovercomethelossesduetothisextrapiping,thusrequiringanadditionalpneumaticdevicetopushthecapturedrodpackingemissionsthroughtheclosedventsystem.Inasituationwherecontractcompressionservicecompaniesorrentalcompaniesareprovidingthecompressorpackages(bothofwhicharerepresentedbytheGCAmembership),mostofthecostofthesesystemsarebornbyourmembercompanies,nottheproducers.However,itistheproducerswhobenefitfromthecaptureofsaidnaturalgas.Thus,theassumedadditionalrevenuefromcapturingtheseleakscannotbebroadlyappliedindeterminingthecosteffectivenessofvariouscontroloptions.Page4GCA Comments Oil and Natural

Gas Sector Compressors

White Paper June 16, 2014 Comment

3: Some

of the studies involved incorporate

faulty or misleading assumptions

that

do not correlate

with compressors operating

at remote
field sites

in the Oil and Natural

Gas sector. The GRIIEPA

study from 1996 that

is referenced

in Table

3-2 of the Compressor

White Paper bases

its assumptions

of emissions

from
the natural

gas production segment

on the idea that there

are

4 seals per compressor.

As the study references

leak rates per seal, this number

is very important

in determining

the emissions

from
the natural

gas production segment

and the compressors
therein. However,
based

on the information

of the member companies

in the GCA and the respective equipment

they operate

in the field,
this number

of seals per compressor significantly overestimates

the emissions

from this industry segment.

A majority

of the compressors

in the natural

gas production segment

are less than 500 HP, where nearly

all (99.95%)

of compressors

will have two seals,

not four. Even with larger compressors,

a number of these

are also equipped

with two seals

(or throws),

not four. Our member companies estimate that the average number

of seals per compressor

across their fleets operating

in the natural

gas production segment

is actually

2.6. This fact would thus reduce

the estimated emissions

from this industry segment

by about 35%.
For compressors<

500 HP, the reduction would

be roughly 50%. These facts therefore support

the assertion

that this industry segment should remain excluded

from further regulation,

as discussed
above
and

in the TSDs published

for 40 CFR

60 Subpart 0000. The emission
levels reported

in the 2014 GHG Inventory

are reportedly
based

on the 1996 GRIIEPA
study,

but the numbers
don't align.
The 2014 GHG Inventory reports

that average emissions

from small compressors

are 286.59 scfd/compressor

and 16,269.75 scfd/compressor

for large compressors

(Table A-125, Annex

3). However,

the GRIIEPA

study reports

that emissions

from small production compressors

are 12.09- 267.57 scfd/compressor

and 15,195.07 scfd/compressor

for large compressors
(Tables

5-2 and 5-3), while processing segment compressors

are 11,203.29 scfd/compressor

(Table 5-5). These 2014 GHG Inventory

and GRIIEPA numbers appear

to include emissions

from

all compressor emissions

(i.e., blowdowns, equipment

leaks, miscellaneous,

and compressor

seals),

so

it is misleading

and should

be evaluated properly
when determining

the cost effectiveness

of regulation

on compressor

seals. Rod packing replacement

for compressor

seal leaks will not impact

the majority

of compressor emissions,

as compressor

seal leaks typically comprise

less than 25%

of the total emissions

from a compressor, according

to the 1996 GRIIEPA
study. In section 4.2.1,

the White Paper references

REM Technology

and average

fuel gas savings
from installation

of

a "gas recovery system". However,

the Fact Sheet referenced discusses Air/Fuel
Ratio Controls,

not

a gas recovery system used

to capture compressor

seal leaks. Furthermore,

the fuel gas savings referenced

are from improved operation

of the engine and have

no correlation

to the compressor

or the effectiveness

of the compressor

rod packings. Page

5GCA Comments Oil and Natural

Gas Sector Compressors

White Paper June

16, 2014 Finally, assuming

the fuel gas savings

are an ancillary benefit

to the fuel gas recovery system, contract compression

service companies

and rental companies represented

by the GCA

do not benefit from this fuel gas savings, though
they would more than likely bear the cost

of installation of the REM technology.

REM technology

is not common

in the Oil and Gas industry,

the safety concerns

are serious

and should

be thoroughly evaluated,

and the cost

of

a more advanced AFRC to account

for the additional

fuel source

is not feasible

for compressor packages operating

in remote areas that are typically much smaller

and operating
under lower pressures.

Thus,

the fuel gas savings potentially associated

with the installation

of this AFRC

do not apply

in

a discussion about compressor

rod packing controls. Comment

4: The definition

of centrifugal compressor
should be referenced

from preexisting regulations

to improve clarity

and consistency between rules. In the White Paper,

the EPA defmes

a centrifugal compressor

as "Any machine

for raising

the pressure

of

a natural

gas by drawing

in low pressure natural

gas and discharging significantly

higher pressure natural

gas by means

of mechanical rotating vanes

or impellers". This definition

is broad
and could inadvertently
include compressors

that
do not operate

the same as typically regulated centrifugal compressors.

When evaluating centrifugal compressors,

it is important

that EPA maintain

a consistent definition

of the applicable source. Therefore,

the GCA instead would suggest referencing

the existing definition

of centrifugal compressor

in NSPS 0000,

to avoid unnecessary ambiguity.

That definition
reads, "Any machine

for raising

the pressure

of

a natural

gas by drawing

in low pressure natural

gas and discharging significantly higher pressure natural

gas by means

of mechanical rotating vanes

or impellers.
Screw, sliding vane,
and liquid ring compressors

are not centrifugal compressors." Summary The GCA wishes

to thank

the EPA
for the opportunity

to make
the preceding comments

and for its thoughtful consideration

of the same.

If you have any questions regarding

this submittal please contact

the GCA

via our management company (NACM)

at 972-518-0019

or Erin Badough, Environmental Committee Chairman,

at 281-836-7514. Sincerely, **~(_** __

__ _____ Erin Badough,

PE Environmental Committee Chairman,

Gas Compressor Association Page

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