ISSUE DATE: 4/01/2011 

PROGRAM INFORMATION BULLETIN NO. P11-21

FROM: LINDA F. ZEILER

 Acting Director of Technical Support 

 KEVIN G. STRICKLIN

 Administrator for

 Coal Mine Safety and Health

NEAL H. MERRIFIELD

 Administrator for Metal and Nonmetal

 Mine Safety and Health

SUBJECT: Reissue of P07-14 - Fastenings Used for Joints of Flame-

 Arresting Paths on Intake or Exhaust Systems for Permissible

 Diesel-Powered Equipment

Who needs this information?

Mine Safety and Health Administration (MSHA) personnel, underground coal mine 

operators, underground metal and nonmetal operators, miners’ representatives, mine 

equipment manufacturers, and repair/rebuild facilities should have this information.

Why is MSHA issuing this Program Information Bulletin?

This Program Information Bulletin (PIB) re-emphasizes the Title 30 Code of Federal 

Regulations (30 C.F.R.) requirement that fastenings used for joints of flame-arresting 

paths on intake or exhaust systems for permissible diesel-powered equipment should 

be used only for attaching parts that are essential in maintaining the explosion-proof 

integrity.

MSHA’s Approval and Certification Center (A&CC) identified permissible dieselpowered equipment operating in underground mines where brackets were attached to 

an alternate air intake port cover and exhaust manifold using the flame-arresting path 

fasteners that attach the cover and exhaust manifold.
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What permissible diesel-powered equipment does this PIB address?

This PIB addresses permissible diesel-powered equipment that is approved under 30 

C. F. R. Part 36. This equipment is equipped with a permissible diesel power package 

(safety component system) approved under 30 C. F. R. Part 7, Subpart F or certified 

under 30 C. F. R. Part 36.

What is the requirement for fastenings used for joints of flame-arresting paths on 

intake or exhaust systems on a permissible power package (safety component 

system)?

30 C.F.R. § 7.98(q)(5) states: 

“Fastenings used for joints of flame-arresting paths on intake or exhaust systems shall 

be used only for attaching parts that are essential in maintaining the explosion-proof 

integrity. They shall not be used for attaching brackets or other parts.”

30 C.F.R. § 36.20(a) states:

“MSHA will test only equipment that in the opinion of its qualified representatives is 

constructed of suitable materials, is of good quality workmanship, based on sound 

engineering principles, and is safe for its intended use.” 

In addition, 30 C.F.R. § 18.32(f) which was applied when the A&CC issued many of the 

power package (safety component system) certifications, states:

“Fastenings used for joints on explosion-proof enclosures shall not be used for attaching 

nonessential parts or for making electrical connections.”

What are the potential hazards of using flame-path fasteners to attach nonessential 

parts, brackets, or for making electrical connections?

Using flame-path fasteners to attach a nonessential part or bracket presents three

potential hazardous conditions.

The first hazardous condition exists if the part is attached with a fastener whose length 

does not provide proper thread engagement. The additional thickness of the part or 

bracket may decrease the amount of thread engagement. Without proper thread 

engagement, the power package no longer complies with § 7.98(p)(2)(ix) of 30 C.F.R.

Part 7 Subpart F or § 18.31(a)(6) of 30 C.F.R. Part 18 Subpart B, and the holding 

capability of the fastener is reduced.

The second hazardous condition exists when one of the flanges of the joint has blind 

holes and more than one length fastener is used to accommodate the bracket. In this 

case, if a longer fastener is inadvertently placed in one of the blind holes, where the 

bracket is not located, the fastener may bottom out before the joint is tight. This will 

result in a loose joint and an open flame-path. 
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The third hazardous condition exists when a part may be exposed to additional 

vibration due to its configuration and mounting location. The additional vibration on 

the component and mounting bracket may degrade the holding capability of the 

fastener and cause the fastener to loosen. 

What action should be taken?

Examine the flame-path joint fasteners on your permissible power package (safety 

component system) intake and exhaust components. Contact one of the A&CC contacts 

below if these fasteners are used to attach nonessential parts, brackets, or for making 

electrical connections. The A&CC will evaluate the equipment approval documentation 

on file at the A&CC to determine the necessary action. The A&CC will contact the 

equipment approval holder to develop a plan to retrofit the equipment as needed. 

What is the background for this PIB?

The A&CC discovered two different brackets attached using flame-path joint fasteners 

during a field modification inspection. The fuel rack shutdown cylinder bracket and 

alternate air intake port surge tank bracket were attached using flame-path joint 

fasteners.

The A&CC is working with the equipment manufacturer to correct the equipment in the 

field.

What is MSHA's authority for this PIB?

The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq.; 30 

C.F.R. § 7.98(p)(2)(ix), § 7.98(q)(5), § 18.31(a)(6), § 18.32(f), and § 36.20(a).

Internet Availability

This information bulletin may be viewed on the Internet by accessing MSHA's home 

page at http://www.MSHA.gov and then choosing Compliance Info, and Program 

Information Bulletins. 

Who are the MSHA contact persons for this PIB?

Coal Mine Safety and Health, Safety Division

Charles Carpenter, (202) 693-9532

E-mail: carpenter.charles@dol.gov

Metal and Nonmetal Safety and Health

Neal H. Merrifield, (202) 693-9600

E-mail: merrifield.neal@dol.gov

Technical Support, Approval and Certification Center

Gary Clark, (304) 547-2068

E-mail: clark.gary@dol.gov
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Technical Support, Approval and Certification Center

Steve Cole, (304) 547-2304

E-mail: cole.stephen@dol.gov

Who will receive this PIB?

MSHA Program Policy Manual Holders

Underground Mine Operators

MSHA Enforcement

Mine Equipment Manufacturers

Repair and Rebuild Facilities

Miners' Representatives

Special Interest Groups