# Global Products and Services, Baker Hughes — Hazardous Materials Safety Interpretation

**Citation:** 13-0013  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 2013-04-10

13-0013 response to Global Products and Services, Baker Hughes concerning 173.306.

## Document text

<<<PAGE 1>>>

U.S. Department
of Transportation
Pipeline and Hazardous
Materials Safety
Administration
1200 New Jersey Avenue, SE
Washington, D.C. 20590
APR 1 0 2013
Mr. Aubrey R. Campbell
Senior Dangerous Goods Safety Advisor
Global Products and Services, Baker Hughes
2001 Rankin Road
Houston, TX 77073
Ref No. 13-0013
Dear Mr. Campbell:
This responds to your December 10, 2012letter requesting clarification ofthe Hazardous
Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to accumulators. In your
letter, you describe and provide a picture illustrating two accumulators that are part of a
"Thumper Unit" that is used at well drilling sites as an integral component of the oilfield
operation. Each accumulator is offered for transport pre-charged with nitrogen gas to a
maximum pressure of2,000 psig (at 70°F). Additionally, each has a manufacturer's burst
pressure rating of 12,000 psig, which is six times greater than the maximum pre-charged
pressure. Based on this information, it is your understanding that the "Thumper Unit" is
excepted from the requirements of the HMR as specified in§ 173.306(f).
Your understanding is correct. In accordance with § 173 .306( ±)(1 ), accumulators installed in
motor vehicles, construction equipment, and assembled machinery and designed and fabricated
with a burst pressure of not less than five times their charged pressure at 70 °F., when shipped,
are not subject to the requirements of the HMR. Based on the information you provided, the
"Thumper Unit" meets the conditions for exception from the HMR.
I hope this information is helpful. If you have further questions, please contact this office.
Sincerely,
;?425~
Robert Benedict
Chief, Standards Development Branch
Standards and Rulemaking Division

<<<PAGE 2>>>

ber ~w1~~V1
.SI/3 .3o[Jf~)
Accumulaforr
l:? -DO l3
fl:t:~:<cJ
BAKER
HUGHES
2001 Rankin Road
Houston, TX 77073
Phone: (713) 879-2658
December 10, 2012
Office of Hazardous Materials Standards
Pipeline and Hazardous Materials Safety Administration,
Attn: PHH-10
U.S. Department of Transportation
East Building, 1200 New Jersey Avenue, SE
Washington, DC 20590-0001
Re: Letter of Interpretation
Dear Office of Hazardous Materials Standards:
Baker Hughes, Inc. (BHI) requests a letter of interpretation regarding the provisions in Title 49 Code
of Federal Regulation (CFR) Part 173.306(f)(1) applicable to limited quantities of compressed gases.
Specifically, BHI offers an accumulator called the "Thumper Unit" for transport with Nitrogen
compressed gas, 2.2, pre-charged to a maximum of 2000 psig. The Thumper Unit (see attached
photo) is used at oil and natural gas well sites as an integral component of the oilfield operation.
The manufacturer's burst pressure rating on each accumulator cylinder (2) in the Thumper Unit is
12,000 psig {see attached specification sheet.) We calculated the burst pressure as six times greater
than the maximum pre-charged pressure at 70 degrees. Given this calculation, we understand that
the Thumper Unit, as described, is excepted for all requirements of subchapter C according to Part
173.306(f)(1). Please provide clarification of this determination.
Sincerely,
Senior Dangerous Goods Safety Advisor
Global Products and Services, Baker Hughes

<<<PAGE 3>>>



<<<PAGE 4>>>

090A80 Accumulators a,ooo Psi t2o7 aar) 'Tobul
r ~~;~~~----------_G_--~-~--.-~-AP._'A_C_ITY--+-F-LU-ID_c_Ar-·P._'A~C-ITY~~~~D~RY~-,WE--~-I~G~HT~~~~~~~-~A~-~D~I--M_E=N~S~IO~N----~_,B,_.------------=-1
Gallon I Liters Lbs. Kg. ln. mm. ln. mm. l
090A30-20NV1K ! 612 10,030 2.5 l 9 192 87 22 559 23.25 591 I
090A30-40NV1K 1,191 19,515 5 19 ' 256 ' 116 34.625 879 35.875 912 i
090A30-60NV1K 1.765 28,925 7.5 28 320 145 47.25 1200 48.5 1,232 i
---~--------1----+---~r-----+----1-----+-----+-----~--~
I 090A30-80NV1K l 2,347 38,465 10 38 385 175 60 1524 61.25 1,556 i
lo9oA30-100NV1K I 2,918 47,819 12.5 47 448 203 72.5 1841 73.75 1,873 I
j 090A30-120NV1 K l 3,495 ·-5-7·,-26-6--+
1---15-+--5-7--ir-5-13-~2-3-2--+-8-5-.1-25-t--21_6_2 -t--8-6.-37-5-+-2-, 1_9_4___,
1----------+-----+----+----·-~~----+----+-----t-------+---+------l-----------l
090A30-140NV1K I 4,071 66,713 17.5 66 576 I 261 97.75 2483 ' 99 2,515
:----------- ---·-------+----+-------!·-------+ -----~-----tf--------t-------i
090A30-160NV1K : 4,648 76,160 20 76 641 291 110.375 2804 111.625 2,835 ;
. ---+----"·-------------------- ---·--·--!---·---+----+------ ····· -----+----+-
ti90A30-200N:'1KII, 5,806 95,148 25 95 770 349 I 135.75 3499 137 3,480
~90A30-240NV1K : 6,959 114,042 30 114 898 407 161 4089 162.25 4,121 I
l 090A30-320NV1K I 9,265 151,831 40 I ~151 1,154 523 211.5 5372 212.75 5,404
L~90A3E~-~~~~ 11 ,571 189_,6_19 ___ _,___5_0 __ _,___1 8_9____c_1 ,4_1_1 _ ___,__ ____ 6_4_0 ___ -<-~2_6 __ 2____, ____ 6~6_55_~..__26_3_.2_5 __,__6_,6_87____,1
---------A
-----B----___ __, _ __,, -L-1-1/4" (32mm)
I
SAE2"
4-BOLT
l
9" DIA
· J '
1 , ., (229mm)
!· hI . ~'·· ,
: -. -, ~ I ' -. '"' ·,,~''·,--.,, I
J~"f--L~-~L..li/'---'/ :LlJL' c..." <L.L.! .....2:\-~:-
-
-
~
~
/ ~ -,,_
~.. )·""'-) ~ ,.,.--..,//<.--.....,./ / ,r:-:-,;/ ,...-..c,>
\.,~) (,~/. (~Q) (!!) (1f) lj_~) (.~~)
GENERAL DESIGN DATA
MAXIMUM WORKING PRESSURE .................................................................................. 3,000 PSI MAXIMUM PROOF PRESSURE ........................................................................................ 4,500 PSI
MINIMUM BURST PRESSURE ......................................................................................... 12,000 PSI
(207 Bar)
(310 Bar)
(827 Bar)
OPERATING TEMPERATURE (Buna/Nitrile) ........................................................ -20° TO +200° F (-28~ to 939 C)
STANDARD SEAL MATERIAL FOR PETROLEUM BASE OIL.
SEALS AVAILABLE FOR OTHER FLUIDS.
NOTE: Optional porting/mounting configurations available on request
090A30_1112
Phone: 803-245-5111 Fax: 803-245-2838 Tobul Accumulator, Inc. Bamberg, sc USA www.Tobul.com

<<<PAGE 5>>>

080A30 Accumulators a,oooPSI(2o7aar> 'Tobul
090A30 SERIES PARTS BREAKDOWN (CATALOG STANDARD 090A30·*NV1K)
--
11TEM
NO. PART NO. DESCRIPTION NO. REQ'D
'
1 HG61MB23-K HEAD, FLUID, 2" SAE 4 BLT CODE 61 1
2 SB4T112 I SEAL, BACKUP, TEFLON 2
~
3 S04N112 SEAL, 0-RING, HEAD, BUNA-N 2
C72TA61-176 CYLINDER, 090A30-20, 2.5 GALLON, 9 LITER
C72TA61-277 CYLINDER, 090A30-40, 5 GALLON, 19 LITER
C72TA61-378 CYLINDER, 090A30-60, 7.5 GALLON, 28 LITER
C72TA61-480 CYLINDER, 090A30-80, 10 GALLON, 38 LITER I
C72TA61-580 CYLINDER, 090A30-100, 12.5 GALLON, 47 LITER
I C72TA61-681 CYLINDER, 090A30-120, 15 GALLON, 57 LITER
4 ; 1
! C72TA61-782 CYLINDER, 090A30-140, 17.5 GALLON, 66 LITER I !
C72TA61-883 CYLINDER, 090A30-160, 20 GALLON, 76 LITER
C72TA61-1 086 CYLINDER, 090A30-200, 25 GALLON, 95 LITER
C72TA61-1288 CYLINDER, 090A30-240, 30 GALLON, 114 LITER
C72TA61-1692 CYLINDER, 090A30-320, 40 GALLON, 151 LITER
C72TA61-2096 CYLINDER, 090A30-400, 50 GALLON, 189 LITER
5 P61MH33T PISTON, ALUMINUM 1
6 SB4T113 SEAL, BACKUP, TEFLON 6
ST4N114 SEAL, PISTON, "T'' SEAL, BUNA-N 3
7 3A-175 BALL, CHECK VALVE 2
S01V.114 SEAL, 0-RING, CHECK VALVE, VITON® 2
8 3A-24 SCREW, RETAINING, CHECK VALVE 2
4A-135 SPRING, CHECK VALVE 2
9 NP-300 NAMEPLATE 1
10 HG61MB23-1 HEAD, GAS, Y2-20 1
OPT DR-ASSY-32 RUPTURE DISK ASSM (OPTIONAL) 3200 PSI 1
12 B-.37GB 16S6-B BOLT, CARBON STEEL, 3/8-16 x% 2
13 3A-283 SS VALVE, GAS, 3K, V2-20 UNF-3A 1
14 3A-754D GUARD, VALVE, ALUMINUM 1
--
---~'
(*DENOTES INSERTION POINT FOR UNIT VOLUME DESIGNATION, i.e., 80 = 10 GALLON VOLUME)
COMPLETE SEAL KITS
NEW PART NUMBER TYPE OLD PART NUMBER
SK090A30-NT BUNA-N 9A30-G40T-NST
SK090A30-VT VITON® 9A30-G40T-ETI
SK090A30-ET EPR 9A30-G40T-HTI
Specify seal material by selecting appropriate material code- "N"= Buna-N; "B"= Butyl; "E"= EPR; "V"= FKM (Viton®)
090A30_1112
Phone: 803-245-5111 Fax: 803-245-2838 Tobul Accumulator, Inc. Bamberg, sc USA www.Tobul.com

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2013/130013.pdf>
- Source ID: `phmsa`
- SHA-256: `b974cbd923dc7acc4ac29855c5717f07e2e4132b95ef9d449b0eb7f804eb3973`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-24T13:21:19.147Z
- Document slug: `phmsa-interpretation-13-0013`

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