CPI Fasteners, Anchors & Hardware 2 — Questions and Answers
Question 1: What is the purpose of a lock washer used with a bolt and nut assembly?
- To increase the tensile load capacity of the bolt
- To prevent the nut from loosening due to vibration (Correct answer)
- To distribute the clamping load over a larger surface area
- To act as a seal against moisture ingress
Correct answer: To prevent the nut from loosening due to vibration
Lock washers (split-ring or toothed) bite into both the nut and the mating surface to resist rotation and prevent the assembly from loosening under vibration or dynamic loads.
Question 2: A chemical (adhesive) anchor offers which primary advantage over a mechanical expansion anchor in cracked concrete?
- Chemical anchors are easier and faster to install
- Chemical anchors bond to the concrete and perform reliably in cracked concrete conditions (Correct answer)
- Chemical anchors are less expensive than mechanical anchors
- Chemical anchors can be removed and reused after curing
Correct answer: Chemical anchors bond to the concrete and perform reliably in cracked concrete conditions
Chemical anchors fill and bond within the drilled hole, making them effective in cracked concrete where mechanical expansion anchors can lose clamping force as cracks widen.
Question 3: When selecting fasteners to connect aluminum components, which material should be avoided to prevent galvanic corrosion?
- Stainless steel 316
- Aluminum rivets
- Zinc-coated steel (Correct answer)
- Nylon
Correct answer: Zinc-coated steel
Zinc-coated (galvanized) steel and plain steel fasteners are galvanically incompatible with aluminum in wet environments, accelerating corrosion; stainless 316 or aluminum fasteners are preferred.
Question 4: What does the 'pullout strength' of an anchor refer to?
- The force required to rotate the anchor during installation
- The maximum tensile force the anchor can resist before being pulled out of the base material (Correct answer)
- The shear force capacity of the anchor in side-loaded applications
- The torque specification listed on the anchor packaging
Correct answer: The maximum tensile force the anchor can resist before being pulled out of the base material
Pullout strength (tensile capacity) is the maximum axial load that can be applied along the anchor's axis before it is extracted from the base material.
Question 5: Which type of rivet is used when only one side of the workpiece is accessible during installation?
- Solid rivet
- Blind (pop) rivet (Correct answer)
- Drive rivet
- Split rivet
Correct answer: Blind (pop) rivet
Blind (pop) rivets are specifically designed for one-sided access; the mandrel is pulled to expand the tail end without requiring access to the back of the material.
Question 6: The proof load of a bolt is defined as:
- The maximum load the bolt can carry without breaking
- The load at which the bolt permanently deforms (yields)
- The load a bolt can sustain without permanent deformation, used as the installation target (Correct answer)
- The fatigue load rating after one million cycles
Correct answer: The load a bolt can sustain without permanent deformation, used as the installation target
Proof load is approximately 90–93% of yield strength and represents the maximum axial load a bolt can sustain without any permanent set; it is the basis for tightening specifications.
Question 7: When installing masonry screws (e.g., Tapcon) into concrete, what type of drill bit must be used?
- High-speed steel (HSS) twist bit
- Titanium-coated wood bit
- Carbide-tipped masonry bit (Correct answer)
- Cobalt step drill bit
Correct answer: Carbide-tipped masonry bit
Carbide-tipped masonry bits are required to drill into concrete because carbide can withstand the abrasive hardness of cured concrete without dulling rapidly.
CPI Fasteners, Anchors & Hardware 2
What is the purpose of a lock washer used with a bolt and nut assembly?