5033
Rev.
02/2002
VACUUM
VESSEL SAFETY
(Formerly
Fermilab Engineering Standard SD-41)
Vacuum vessels, including evacuated chambers and
insulating jacketed dewars,
pose a potential hazard to equipment and personnel from rupture or implosion.
This chapter specifies the procedure to be followed in designing, fabricating,
testing, and using vacuum vessels in order to reduce hazards.
All vessels within the scope of this chapter shall have a
written Engineering Note, as described in this chapter.
This chapter applies to any vacuum vessel used at
Fermilab except:
1. Any vacuum vessel whose inside diameter
or cross section diagonal is under twelve inches with no limitation of length.
2. Any portions of beam pipes buried
underground.
3. Any vessel with a volumetric capacity
of less than 35 cubic feet.
4. Any vessel under external pressure
whose product P x V is less than 515 (psi) (cu. ft.), where P is the external
differential MAWP and V is the volumetric capacity.[1]
5. Thin vacuum windows for beam lines are specifically excluded from this chapter, and are covered under FESHM Chapter 5033.1.
The Code -ASME Boiler and Pressure
Vessel Code Section VIII Divisions 1 and 2. The revision of the Code to be
applied to a given vessel is the latest revision at the time of the vessel's
fabrication.
Vacuum Vessel - any vessel having
atmospheric pressure outside the vessel and a pressure less than atmospheric
inside the vessel, or any vessel which is operated with a differential pressure
greater on the outside than on the inside, excepting those operating under an
external pressure greater than one atmosphere, which are covered under FESHM
Chapter 5031, and excepting thin windows commonly used in beam lines.
Engineering Note - a written analysis
demonstrating that a given vessel satisfies the requirements of this chapter.
Qualified Person – a person who, by possession
of a recognized degree or certificate of professional standing, or who, by
extensive knowledge, training and experience, has successfully demonstrated the
ability to solve or resolve problems relating to the subject matter.
External Design Pressure - The
external design pressure or maximum allowable external working pressure (MAWP)
shall be greater than or equal to the maximum expected operating pressure
differential. Reference ASME Code Section VIII Div. 1 Part UG28(e)
Volumetric Capacity - the volume of water the
vessel can hold or store. (If another vessel or object is contained inside the
vacuum vessel, the object's volume should be subtracted out)
The division/section head who controls the area of
operation of the vessel is responsible for carrying out the requirements of
this chapter. He shall arrange for the
review of the Engineering Note by a qualified person. He shall certify vessel compliance with this chapter by signing
the Engineering Note and shall maintain an open, updated file on all vacuum
vessels located in his areas of operation.
After certification, the Fermilab engineering standard conformance label
shall be attached to the vessel. The
original of the Engineering Note shall be placed into the Laboratory Vacuum Vessel
master file maintained by the ES&H Section.
The ES&H Section shall audit the divisions and
sections on their compliance to this chapter.
The Mechanical Safety Subcommittee (MSS) and/or Cryogenic
Safety Subcommittee (CSS) shall serve the division/section heads and ES&H
Section in a consulting capacity on all vacuum vessel matters. These committees may propose appropriate
modifications to this chapter as necessary.
Changes in policy and responsibility shall be recommended by the
Laboratory Safety Committee after consulting with the division/section
heads. Changes in procedure shall be
recommended by the Mechanical Safety Subcommittee and/or Cryogenic Safety
Subcommittee.
Vacuum vessels shall be designed to ensure that allowable
stresses are not exceeded and to ensure that the vessel is stable (resistant to
buckling). This chapter includes
adherence to the ASME Boiler and Pressure Vessel Code. The ASME Code is not mandatory for vessels
with an external pressure not exceeding 15 psi under Section VIII Paragraph
U-1(c-8), but the design rules may be applied.
Under Section VIII Paragraph UG-28(f), such vessels may be U-stamped.
Vacuum vessels covered by this chapter are not required
to be U-stamped, but shall be designed according to the appropriate design
rules in the Code revision current at the time of design, unless a
determination has been made that another standard is more applicable. The division/section head or designee shall
make that determination in consultation with the MSS and CSS.
For the purposes of this chapter, applicable portions of
the ASME Code include:
·
Section VIII Div. 1 Parts UG28, UG29, UG 30, UG32, UG33,
UG34, UG37 to UG42, UG80.
·
Section VIII Div. 1 Appendix 9
·
Section VIII Div. 1 Appendix 13 paragraph 13-14
·
Section VIII Div. 2 Appendix 1
·
Section VIII Div. 2 Appendix 2
·
Section VIII Div. 2 Appendix G paragraph G112
The Code explicitly excludes vessels with internal
pressure less than 15 psig, but portions of the Code will be used to satisfy
this chapter:
a.
ASME Code allowable stresses shall be used. For materials not included in tables of
Section II, allowable stresses shall be calculated as described in the ASME
Code Sec. VIII Div. 1 Appendices P & Q and Div. 2 Appendix J.
b.
Stresses and vessel stability shall be calculated as
described in the Code. Finite Element
Analysis (FEA) may be used to refine stress calculations or model vessel
geometries not described in the Code.
c.
Stresses shall meet allowable stress criteria described
in the Code.
d.
The external pressure for buckling failure predicted by
Finite Element Analysis (FEA), used for shapes not specifically covered in the
Code, shall not be less than 3.5 times the MAWP.
Weld configurations not specifically approved or
prohibited by the Code may be submitted with stress analysis calculations for
approval by the Note reviewer.
All relief devices with a relieving pressure of 15 psid
or greater shall be UV‑stamped.
Reclosing type relief valves with a relieving pressure under
15 psid are not required to be UV-stamped.
Non-reclosing and recloseable type relief devices such as
rupture discs and flip-lids with a relieving pressure under 15 psid are not
required to be UV-stamped. All relief
devices shall be certified by the manufacturer for relieving pressure and flow
rate, or if designed by FNAL, shall be tested according to the Code part UG127
and a test report included in the Engineering Note. Calculations of relief valve sizing shall be included in the
Engineering Note. Reference ASME Code
Parts UG125-136 and CGA Handbook of Compressed Gases Chap. 5
Windows on vacuum vessels shall comply with FESHM 5033.1
1. Preparation of Engineering Note:
An Engineering Note shall be prepared by an engineer or designer for all
existing or new operational vacuum vessels at Fermilab; whether purchased,
in-house built, an experimenter's vessel, a used vessel, or located in an
unmanned area. The format of the Engineering Note is shown in Exhibit A-1. Its
purpose is to allow a reviewer to check the design and installation and to
inform a future user of the vessel parameters.
The Engineering Note shall include design calculations for in-house
built vessels and experimenter built vessels, and the manufacturer's data
reports for purchased vessels if available.
The Note shall also include precautions and operating procedures
necessary for the safe use of the vessel.
2. Review of Engineering Note: All vacuum vessel Engineering Notes shall be
reviewed by an independent, qualified reviewer, other than the author, for
concurrence to this chapter. The
reviewer shall be from a group not reporting to the preparer of the Engineering
Note or his supervisor.
3. Amendment of Engineering Note: Any subsequent changes in usage, operating
temperature, valving, etc., which could affect the safety of the vessel,
requires an amendment to the original Engineering
Note. This amendment shall be
reviewed in the same manner as the original Note.
4. Similar Vessels: Vacuum vessels that are similar to
previously constructed and approved vessels need not have the full engineering
analysis repeated. Adequate
documentation can be provided by referencing the approved engineering analysis
and noting any differences. Acceptance
testing will still be required. For the
purposes of this paragraph, similar vessels mean that the same kinds of
materials and construction techniques are used and similar operating parameters
will be used. The geometry must be
similar, however, this paragraph may be applied if geometry differences do not
affect the engineering analysis or safety.
5. Director's Exception: Exceptions
to the provisions of this chapter shall be allowed only with the signature of
the Laboratory Director or his designee documented in the Engineering
Note. The need for such exceptions is
to be minimized by adherence to the provisions of this chapter. Exceptions are to be identified and submitted
to the Director for review as early in the design process as possible. These exceptions shall only be allowed after
the Director has assured himself that sound engineering practice will be
followed during design, fabrication and test of the vessel. The ES&H Section shall maintain copies
of exceptions for the Director. An exceptional
vessel is hereby defined as one which cannot meet the tenets of this chapter
and therefore requires a Director's Exception.
6. A technical appendix describing
procedures for an Engineering Note analysis is included.
5033TA
TECHNICAL
APPENDIX TO VACUUM VESSEL SAFETY
PROCEDURES AND REQUIREMENTS FOR DESIGN, FABRICATION,
INSPECTION AND TEST
1. Purchased Vessels: All vacuum
vessels purchased by Fermilab or its experimenters shall be made (designed and
fabricated) in accordance with the "Procedure" section of Chapter
5033.
2. In-House Built Vessels: All vacuum vessels built at Fermilab or
experimenter's shops shall be made (designed and fabricated) in accordance with
the "Procedure" section of Chapter 5033.
3. Vessels
with Thin Windows: If the thin windows can be detached from the vessel, the
vessel falls within the scope of this chapter and shall be made (designed and fabricated) in accordance
with the "Procedure" section of Chapter 5033. For testing, a cover plate shall be
substituted for each thin window.
A vacuum
vessel with a thin window that cannot be detached is covered by this chapter,
but only for the vessel itself, not the thin window. The thin window itself is covered under Chapter 5033.1 for thin
windows. For testing of such a vessel,
the maximum allowable differential pressure of the thin window shall not be
exceeded, and the vessel shall be rated at that pressure.
4. Welding Information: (Fermilab
or Experimenter's Welding Shops Only). Welding executed at Fermilab shall be done
in a manner equivalent to a generic welding procedure specified and qualified
under the rules of the A.S.M.E. Boiler and Pressure Code Section IX. The author of the Engineering Note shall
attach a copy of the welder qualification record to the Note.
If the vessel is fabricated at
some other location under the supervision and/or subcontract of an
experimenter, documentation shall be furnished to Fermilab describing: (1) the
materials utilized, (2) the welding procedures, (3) welding qualifications, and
(4) identification of welder. These
documents shall be attached to the original Engineering Note.
5. Existing Vessels In Service: All
such vessels in service need an Engineering Note.
6. Used Vessels: Used Vessels shall be classified as an
existing vessel and will have their previous service taken into account during
the review process. Questionable
vessels or those with unknown histories shall be re-tested per the
"Inspection and Testing" section of this chapter.
7. Non-manned Area Vessels: If a vacuum vessel cannot be made in
accordance with the preceding requirements, it may be installed in a non-manned
area with suitable administrative and physical controls to restrict access when
operating the vessel and restraints to minimize damage in case of failure. The vessel must be clearly and indelibly
identified for use in non-manned areas only and be sufficiently secured to
prevent its removal from the non-manned area.
An Engineering Note shall be completed for all such vessels.
8. Inspection and Testing: The vessel shall be inspected during
fabrication by the designer/engineer for compliance to the standard. All vacuum vessels shall be acceptance
tested by pumping out the vacuum volume before the Engineering Note is
submitted for approval.
For ordinary vacuum vessels the
test pressure shall be full atmospheric pressure differential of 15 psid.
For vacuum vessels not intended
to be pumped out to the full atmospheric pressure differential of 15 psid, the
test pressure shall be 125% of the maximum allowable external differential
pressure, but not more than full atmospheric pressure (15 psid).
Thin windows and other delicate
equipment may be removed for the test of the vacuum vessel. The test shall be documented with a brief
description and the signatures of two witnesses.
An Engineering Note (see technical appendix for note
format) shall be prepared by the designer addressing the topics below for the
vessel, series of vessels, or vessel system, as appropriate. Its purpose is to allow a reviewer to check
the design and installation and to inform a future user/re-tester of the appropriate
vessel parameters. The note shall be
signed and filed as noted in Chapter 5033 under "Special
Responsibilities."
1. Description
and Identification
Obtain a vessel identification number
from the division or section safety officer. Describe the vessel, its purpose,
site location, and how the maximum allowable working pressure (MAWP), internal
or external, was established.
All drawings deemed pertinent to the safety review shall be listed and included. Include in the note a copy of the information on the engineering standard conformance label.
2. Design
Verification
Provide the design calculations. For externally manufactured vessels, a copy of their design calculations is acceptable.
3. System
Relief Verification
In case a vacuum vessel is
pressurized, either intentionally or inadvertently, its relief devices are
important in maintaining safety. Provide a schematic of the vacuum vessel
relief system and appropriate calculations or test results to prove that the
vacuum vessel will not be subject to pressures over its calculated MAWP or
under its maximum external differential pressure. (Note: If the MAWP is greater
than 15 psi, a FESHM Chapter 5031 Engineering Note is required.) Prove that the
relief/reliefs can not be isolated from the vacuum vessel except as allowed by
ASME Code (Reference Sec. VIII Div. 1 Appendix M and Div. 2 Appendix A). The
relief calculation should take in account a failure of any piping or vessel
inside the vacuum vessel, and shall be sized according to the maximum system
flow rate of that piping, and/or a reasonably expected leak rate from the inner
vessel.
4. Operating
Procedures (Optional)
Provide cautions and operating
procedures necessary for the safe use of the vessel.
5. Welding
Information (Fermilab Shop or Experimenter Shops)
Provide the welding information
requested in the technical appendix, "Procedures ...", paragraph 4.
6.
Extended Engineering Note for Exceptional Vessels:
The Note shall be prepared
using the same or similar format as noted on Exhibit A-1, but in addition shall
include the following information.
a. Reason for Exception: Division/Section Head or designee shall provide a statement showing the necessity of a Director's Exception.
b. Analysis/Collapse Test: The system designer shall provide a stress/collapse analysis of all exceptional parts of the vessel. Include data, formula or test results that demonstrate the anticipated safety factor. Source of information shall be referenced.
c. Fabrication: The system designer shall provide a
fabrication procedure, a list of planned and completed inspections and any
other quality control procedures taken.
d. Hazard Analysis: The system designer shall provide a
description of personnel hazards associated with vessel operation and the
methods used for protection. The hazard
analysis shall address vessel application, operating limits and controls,
possible effects in the event of vessel failure and inherent safeguards
provided.
e. Acceptance Test: An acceptance test shall be performed per
this chapter.
Engineering Note for Existing Vessels, Used Vessels and
Non-manned Area Vessels
The division/section head or his designee shall provide a
written record of the decisions, judgments, tests, administrative controls and
hazard analysis that were necessary to approve these types of vessels under
this chapter.
In the event that the Engineering Note cannot be
approved, operation shall be discontinued until appropriate modifications or
administrative safeguards are instituted, or Director's Exception is granted.
A Design Chart for Long Vacuum Pipes and Shells TM-1378
(SCN 0121.585).
Design Charts for Spacing of Vacuum Line Supports TM-1377
(SCN 0121.585).
Design Charts for Vacuum Plates TM-1052 Rev A. (SCN
5540.100).
EXHIBIT
A-1
Vacuum
Vessel Engineering Note
(per
Fermilab ES&H Manual Chapter 5033)
Prepared by |
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Date |
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Div/Sec |
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Reviewed by |
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Date |
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Div/Sec |
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Div/Sec Head |
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Date |
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Div/Sec |
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1. Identification and Verification of Compliance
Fill
in the Fermilab Engineering Conformance Label information below:
This
vessel conforms to Fermilab ES&H Manual Chapter 5033
Vessel Title |
|
Vessel Number |
|
Vessel Drawing Number |
|
Internal MAWP |
|
External MAWP |
|
Working Temperature
Range |
|
Design/Manufacturer |
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Date of Manufacture |
|
Acceptance Date |
|
Director's
signature (or designee) if vessel is for manned area and requires an exception
to the provisions of this chapter.
___________________________________________________________________________
Amendment No. |
Reviewed by: |
Date: |
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Laboratory location
code |
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Laboratory property
number |
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Purpose of vessel |
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List all pertinent drawings
Drawing No. |
Location of Original |
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2. Design Verification
Provide
design calculations in the Note Appendix.
3. System Venting Verification
Can
this vessel be pressurized either internally or externally? [ ] Yes [
] No
If “Yes”, to what pressure? _____________
List
all reliefs and settings. Provide a schematic of the relief system components
and appropriate calculations or test results to prove that the vessel will not
be subjected to pressures greater than 110% beyond the maximum allowable
internal or external pressure.
Manufacturer |
Relief |
Pressure Setting |
Flow Rate |
Size |
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4. Operating Procedure Section
Is
an operating procedure necessary for the safe operation of this vessel?
[ ]
Yes [ ] No (If
"Yes", it must be appended)
Is a testing procedure necessary for the safe
acceptance testing (acceptance testing) of this vessel?
[ ] Yes
[ ] No
If
“Yes”, the written procedure must be approved by the division head prior to
testing and supplied with this Engineering Note.
5. Welding Information
Has
the vessel been fabricated in a Fermilab shop? [ ] Yes [
] No
If "Yes," append a copy of the welding
shop statement of welder qualification.
6. Exceptional, Existing, Used and Non-Manned Area
Vessels
Is
this vessel or any part thereof in the above categories? [
]Yes [ ] No
If "Yes" follow the Engineering Note
requirements for documentation and append to note.
[1] This pressure volume product is equivalent to the vessel energy requiring a pressure vessel engineering note from Lawrence Livermore National Laboratory’s Health and Safety Manual and Mechanical Engineering Design Safety Standards.