ISRI Entrance Examination cheat sheet

Ferrous scrap contains iron and is magnetic; nonferrous scrap (Al, Cu, brass, stainless, Pb, Zn, Ni) contains no iron and is generally nonmagnetic.

ISRI grades use short names + numbers: #1 HMS (heavy melting steel) is plate/structural steel ≥1/4 in thick, ≤5 ft x 2 ft; #2 HMS allows thinner, coated, or rusty material.

#1 Copper (Bare Bright) = unalloyed, uncoated, clean copper wire ≥1/16 in diameter; #2 Copper allows solder, paint, or light oxidation.

Aluminum grades split by alloy and coating: Tense (clean old sheet), Tabor (mixed low-copper), Zorba (shredded mixed nonferrous), Twitch (mixed Al scrap).

Stainless identification: 300-series is nonmagnetic (austenitic) and Ni-bearing; 400-series is magnetic (ferritic/martensitic).

Red metals: copper is reddish, brass is yellow (Cu+Zn), bronze is brownish (Cu+Sn); color plus spark/magnet tests confirm.

Spark test: carbon steel throws long yellow-orange bursts; cast iron throws short red sparks; high-alloy steel throws dull, forked sparks.

Lead is dense, soft, gray, and dull; zinc is bluish-white and brittle; tin is silvery and low-melting - density and bend tests separate them.

Steel is an Fe–C alloy with ≤2.1% C; cast iron has 2.1–4% C plus Si, making it brittle and nonforgeable.

Carbon content raises hardness and tensile strength but lowers ductility and weldability.

Austenitic stainless (300-series) is nonmagnetic because of its FCC crystal structure; cold working can induce slight magnetism.

Aluminum is ~1/3 the density of steel (~2.7 vs 7.85 g/cm³) and forms a protective oxide layer that resists corrosion.

Copper has high electrical (~100% IACS reference) and thermal conductivity; alloying with Zn (brass) or Sn (bronze) reduces conductivity.

Galvanizing coats steel with zinc; zinc fuming during melting requires ventilation and creates a health hazard.

Alloy contamination (e.g., Pb or Bi in Al, Ni in Cu) degrades recycled metal value and may require segregation before sale.

Melting points: Al ~660°C, Cu ~1085°C, Fe ~1538°C - used to plan furnace charges and avoid cross-contamination.

Size reduction: shredders (hammermills) fragment light scrap; balers and briquetters compact for transport and furnace feed.

Shears (guillotine/alligator) cut long or oversized ferrous into furnace-acceptable dimensions.

Sorting methods: magnetic separation (ferrous from nonferrous), eddy-current separation (Al from heavy nonferrous), and density/sink-float.

Hand sorting and X-ray/optical sorting remove alloys, plastics, and contaminants before sale.

Shredder fluff (auto shredder residue, ASR) requires landfill or energy recovery; ferrous and nonferrous fractions are recovered first.

Baling density and bale weight affect freight economics; over-sized bales may be rejected by mills.

Dust, noise, and fire risk rise with shredding; water sprays and spark suppression are standard controls.

Preparation for sale: remove attachments (motors, fluids), drain tanks, and segregate by grade to avoid downgrade penalties.

OSHA 29 CFR 1910 covers general industry; scrap yards follow machine guarding, lockout/tagout, and PPE requirements.

Hazardous waste is regulated under RCRA (40 CFR); scrap must be screened for fluids, batteries, and mercury switches.

Stormwater permits (NPDES) require containment of runoff from scrap piles and treatment before discharge.

Air permits may be required for shredders and furnaces; fugitive dust and metal fume must be controlled.

Lead-acid batteries and mercury-containing devices are universal/hazardous wastes requiring special handling.

Confined-space entry (balers, shredders, tanks) requires atmospheric testing and attendant procedures.

Emergency response: fire suppression, spill kits, and trained first aid are required; reportable releases must be documented.

Recordkeeping: manifests, training records, and inspection logs must be retained per applicable regulations.

Scale calibration and certification are required; truck scales must be tested against certified weights.

Net weight = gross weight (loaded) − tare weight (empty); tickets record both.

Inventory turnover = cost of goods sold ÷ average inventory; measures how fast scrap moves.

Cycle counting verifies physical counts against system records to catch shrinkage and misgrading.

FIFO or weighted-average costing determines inventory value; mix-ups can distort margin.

Material handling equipment includes forklifts, loaders, cranes with grapples, and conveyors; load limits must be respected.

Barcodes/RFID and weigh-ticket systems track inbound/outbound lots and link weight to grade and price.

Storage segregation by grade prevents contamination and preserves resale value.

Scrap prices are quoted per gross ton (2,240 lb) or per pound, depending on grade and market.

Prices track steel mill demand, construction activity, and export demand; ferrous and nonferrous markets move independently.

LME and COMEX provide reference prices for copper, aluminum, and other nonferrous metals.

Hedging with futures or forwards locks in price and reduces exposure to market swings.

Basis = spot price − futures price; basis risk remains even after hedging.

Freight, processing cost, and yield (recovery %) determine net margin per lot.

Contract terms specify grade, quantity, delivery, price basis, and payment terms.

Market reports (e.g., published indices) are used to settle prices and benchmark transactions.

Bill of lading is the contract of carriage and receipt; it lists shipper, consignee, commodity, and weight.

Hazardous materials shipments require DOT placards, shipping papers, and trained personnel.

Export/import of scrap may require licenses, permits, and customs declarations (HS codes classify scrap).

Basel Convention and national rules govern transboundary movement of certain wastes.

Truck weight limits (e.g., federal bridge formula) and axle limits affect load planning and cost.

Rail and barge are lower-cost per ton for bulk scrap; truck is flexible but costlier per ton-mile.

Insurance and cargo claims require documentation of weight, condition, and grade at loading.

Trade terms (Incoterms) define who bears freight, insurance, and risk at each point.

Customer pricing transparency (grade, weight, deductions) builds trust and reduces disputes.

Written purchase agreements specify grade, quantity, price, delivery, and payment terms.

Accounts receivable aging tracks unpaid invoices; credit limits manage risk.

Customer segmentation (industrial accounts vs. retail) drives service and pricing strategy.

Complaint handling: document the issue, verify grade/weight, and resolve per contract terms.

Key performance indicators include tons processed, margin per ton, on-time delivery, and safety incidents.

Regulatory compliance and safety records are part of customer due diligence.

Long-term supply relationships reduce price volatility and improve planning.