MSHA - Directorate of Technical Support A Troubleshooting Guide for
Roof Support Systems


Mechanical Bolts

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ERRATIC TORQUE-TENSION

Possible Cause Solution
A.1 Excessive Thrust Adjust bolter settings and instruct operator in proper installation procedure
A.2 Severe Installation Angle Use angle compensating device if installation angle exceeds 5 degrees
A.16 Plate - Bolt Galling Try hardened washers and replace bolts and/or plates
A.8 Washer Too Soft Replace washers
A.5 Bail/Support Nut Too Strong Replace support nut or anchor
A.11 Defective Plate Replace plates
A.9 Defective Threads Replace bolts or plugs
A.6 Defective Anchor Replace anchors
A.20 Bolt/Anchor Threads Jam Determine cause and contact the manufacturer
A.21 Threads Galled On Installation Determine cause and contact the manufacturer
A.14 Hole Too Short Drill hole 1" longer than the bolt length

EXCESSIVE TORQUE

Replace washers
Possible Cause Solution
A.3 Applied Torque Too High Adjust bolter torque setting
Severe Roof Loading If widespread determine the cause and upgrade the support system
A.2 Severe Installation Angle Use angle compensating device if the angle exceeds 5 degrees
A.17 Plate/Washer Mismatch Replace plate and/or washers
A.1 Excessive Thrust Adjust bolter settings and instruct operator in proper installation procedure
A.5 Bail/Support Nut Too Strong Replace bail/support nut or anchor
A.8 Washer Too Soft
A.16 Plate - Bolt Galling Try using hardened washers
A.20 Bolt/Anchor Threads Jam Determine cause and contact the manufacturer
A.21 Threads Galled On Installation Determine cause and contact the manufacturer
A.9 Defective Threads Replace bolts and/or plugs

HIGH TORQUE/LOW TENSION

Possible Cause Solution
A.1 Excessive Thrust Adjust bolter setting and instruct operator in proper installation procedure
A.2 Severe Installation Angle Use angle compensator if installation angle exceeds 5 degrees
A.16 Plate - Bolt Galling Try using hardened washers or replace bolts and/or plates
A.8 Washer Too Soft Replace washers
A.21 Threads Galled On Installation Determine cause and contact manufacturer
A.20 Bolt/Anchor Threads Jam Determine cause and contact manufacturer
A.5 Bail/Support Nut Too Strong Replace support nut or anchor
A.14 Hole Too Short Drill hole 1" longer than the bolt length
A.18 Anchorage Exceeded Try different type of expansion anchor or use different support system
A.9 Defective Threads Replace bolts or plugs

TORQUE NOT ACHIEVED

Possible Cause Solution
A.15 Hole Diameter Too Large Replace bits
A.1 Excessive Thrust Adjust bolter settings and instruct operator in proper installation procedure
A.3 Applied Torque Too Low/High Adjust Bolter Torque Settings
A.19 Poor Roof Strata Try different type of expansion anchor or use different support system
A.6 Defective Anchor Replace anchors
A.18 Anchorage Exceeded Try different type of expansion anchor or use different support system
A.14 Hole Too Short Drill hole 1" longer than the bolt length

BOLT PULLS THROUGH PLATE

Possible Cause Solution
A.4 Plate-Bolt Mismatch Use a higher grade plate
Severe Roof Loading If widespread determine cause and upgrade the support system
A.12 Plate Hole Too Large Use hardened washers or replace plate if out of spec.
A.2 Severe Installation Angle Use angle compensating device if installation angle exceeds 5 degrees
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use a higher grade plate
A.3 Applied Torque Too High Adjust bolter torque setting
A.17 Plate/Washer Mismatch Replace plates or washers
A.8 Washer Too Soft Replace washers
A.11 Defective Plate Replace plates

WASHER BADLY DEFORMED

Possible Cause Solution
A.2 Severe Installation Angle Use angle compensation device if installation angle exceeds 5 degrees
Severe Roof Loading If widespread determine cause and upgrade support system
A.17 Plate/Washer Mismatch Replace washers or plates
A.12 Plate Hole Too Large Use hardened washers or replace plates if out of spec.
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use a higher grade plate
A.3 Applied Torque Too High Adjust bolter torque setting
A.8 Washer Too Soft Replace washers

PLATE FAILS AFTER INSTALLATION

Possible Cause Solution
A.4 Bolt-Plate Mismatch Use a higher grade plate
Severe Roof Loading If widespread determine cause and upgrade support system
A.17 Plate-Washer Mismatch Replace washers or plates
A.12 Plate Hole Too Large Use hardened washers or replace plates if out of spec.
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use a higher grade plate
A.2 Severe Installation Angle Use angle compensation device if installation angle exceeds 5 degrees
A.11 Defective Plate Replace plates

ANCHOR WILL NOT SET

Possible Cause Solution
A.15 Hole Diameter Too Large Replace bits
A.5 Bail/Support Nut Too Strong Replace bail or support nut
A.20 Bolt/Anchor Threads Jam Determine cause and contact the manufacturer
A.9 Defective Threads Replace bolts or plugs
A.6 Defective Anchor Replace anchors
A.7 Bail/Support Nut Too Weak Replace bail or support nut
A.19 Poor Roof Strata Try different type of expansion anchor or use a different support system

BOLT BREAKS AFTER INSTALLATION

Possible Cause Solution
Severe Roof Loading Use higher grade or larger diameter bolts
A.3 Applied Torque Too High Adjust bolter torque setting
A.10 Defective Bolts Replace bolts
A.9 Defective Threads Replace bolts
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use higher grade or larger diameter bolts
A.2 Severe Installation Angle Use angle compensating device if installation angle exceeds 5 degrees

PLATE FAILS ON INSTALLATION

Possible Cause Solution
A.3 Applied Torque Too High Adjust bolter torque setting
A.4 Plate/Bolt Mismatch Use a higher grade plate
A.2 Severe Installation Angle Use angle compensating device if installation angle exceeds 5 degrees
A.12 Plate Hole Too Large Use hardened washers or replace plates if out of spec.
A.17 Plate/Washer Mismatch Replace washers or plates
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use higher grade plate
A.11 Defective Plate Replace plates

LOOSE PLATE

Possible Cause Solution
A.14 Hole Too Short Drill hole 1" longer than the bolt length
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact
A.19 Poor Roof Strata If roof is broken up around the plate use a larger sized plate or reduce the installed load. If this does not correct the problem, try different type of expansion anchor or use a different support system (see A.18 Anchorage Exceeded)
A.15 Hole Diameter Too Large Replace bits
A.20 Bolt/Anchor Threads Jam Determine cause and contact the manufacturer
A.18 Anchorage Exceeded Try different type of expansion anchor or use a different support system

BOLT BREAKS ON INSTALLATION

Possible Cause Solution
A.3 Applied Torque Too High Adjust bolter torque setting
A.2 Severe Installation Angle Use angle compensating device if installation angle exceeds 5 degrees
A.5 Bail/Support Nut Too Strong Replace support nut or anchor
A.10 Defective Bolt Replace bolts
A.9 Defective Threads Replace bolts
A.20 Bolt/Anchor Threads Jam Determine the cause and contact the manufacturer
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve the surface contact

PLATE CRACKS

Possible Cause Solution
Plate Cracks Extending Through The Embossment Discontinue use and contact manufacturer
Small Cracks Around Hole Evaluate plate/bolt compatibility

SPRINGY BOLT

Possible Cause Solution
A.14 Hole Too Short Drill hole 1" longer than the bolt length
A.20 Bolt/Anchor Threads Jam Determine the cause and contact the manufacturer
A.21 Threads Galled On Installation Determine the cause and contact the manufacturer
A.5 Bail/Support Nut Too Strong Replace bail/support nut or replace anchor
A.6 Defective Anchor Replace anchor
A.9 Defective Threads Replace bolts or plugs

ANCHOR BREAKS ON INSTALLATION

Possible Cause Solution
A.15 Hole Diameter Too Small Replace bits
A.22 Anchor Pre-Expanded Reset plugs
A.5 Bail/Support Nut Too Strong Replace bail/support nut
A.7 Bail/Support Nut Too Weak Replace bail/support nut
A.6 Defective Anchor Replace anchor

WASHER CRACKS

Possible Cause Solution
A.8 Washer Too Hard Replace washers
A.2 Severe Installation Angle Use angle compensation device if installation angle exceeds 5 degrees
A.12 Plate Hole Too Large Replace plates
A.23 Irregular Roof Surface Use wedges and/or cap blocks to improve surface contact or use higher grade plates
A.17 Plate/Washer Mismatch Replace plates or washers

EXCESSIVE BLEED OFF

Possible Cause Solution
A.19 Poor Roof Strata Try different type of expansion anchor or use different support system
A.3 Applied Torque Too High Or Low Adjust bolter torque setting
A.4 Bolt - Plate Mismatch Use higher grade plates
A.15 Hole Diameter Too Large Or Small Replace bits
A.6 Defective Anchor Replace anchors

BOLT/PLUG THREADS STRIP

Possible Cause Solution
A.13 Limited Thread Engagement Replace bolts and/or anchors
A.21 Threads Galled On Installation Determine cause and contact manufacturer
A.9 Defective Threads Replace bolts and/or anchors
A.6 Defective Anchor Replace anchors