SOP-EQ-006 Rev 2 — Diamond Ground Piranha III Tungsten Grinder

Equipment: Piranha III Tungsten Grinder (EQ-006)

Location: Bay 3

Approved by: Marty Howe, Welding Instructor

Approval date: 2026-05-25

Linked records: HA-EQ-006 · PM-EQ-006 · TR-EQ-006

Standards basis: OHSA s.25 (general duty); O.Reg 851 s.24 (machine safety), s.84 (rotating equipment), s.85 (lockout), s.105 (PPE); CSA Z460-13 (cord/plug LOTO); CSA Z432 (Machine Safeguarding); CSA W117.2 cl. 10.4 (electrode preparation); CSA Z94.3 (eye/face protection); CSA Z94.4 (respiratory protection); ACGIH TLV for thorium dust (alpha emitter); Health Canada radiation protection guidance (thoriated tungsten).

Machine Specs

Specification	Value
Manufacturer	Diamond Ground Products
Model	Piranha III (DGP-PG3-A)
Motor	500W, 1/3 hp
Wheel speed	1700 RPM
Voltage	110/230V switchable (UA46 setting: 110V)
Weight	32 lbs
Wheel	6" diamond, 300 grit standard (DGP-PG1425)
Collets	Universal — 6 sizes (1/16" to 1/4")
Protection	Circuit breaker, sliding dust shield, 100% containment housing

⚠ Danger Thoriated tungsten dust (ThO₂) is radioactive. NEVER grind without P100 respirator confirmed in place and dust shield closed. NEVER use compressed air to clean — disperses radioactive particulate.

PPE Required

⊙ P100 half-face respirator — MANDATORY before motor start (thoriated tungsten dust)

⊙ CSA Z94.3 safety glasses

⊙ CSA Z94.2 hearing protection (high-frequency motor whine)

⊙ Cotton or leather gloves — NO synthetic

⊙ CSA Z195 Grade 1 safety footwear

Pre-Use Inspection

Confirm cord intact, no nicks; three-prong grounded plug
Verify voltage selector matches outlet (110V at UA46)
Inspect diamond wheel for chips, cracks, or flat spots — replace if any present
Confirm dust shield slides freely and locks in CLOSED position
Verify dust receptacle <50% full
Select universal collet matching tungsten diameter (1/16, 3/32, 1/8, 5/32, 3/16, 1/4)
Verify pin vise jaw clean — no embedded tungsten fragments

Operation

Tungsten Setup

Select correct collet for tungsten diameter
Insert tungsten into pin vise leaving 3/4" exposed beyond jaw
Tighten pin vise jaw finger-tight on tungsten — do not over-torque
Verify tungsten is straight in pin vise (no visible bend)
Set grind angle per WPS (15° thin material; 30° general purpose, UA46 standard)
Confirm dust shield CLOSED before motor start

Grinding the Tip

Power on motor — confirm 1700 RPM steady
With motor running, insert pin vise into machine collet
Apply light pressure — let the wheel do the work, do not force
Rotate pin vise slowly to maintain symmetric point and longitudinal striation
Withdraw pin vise after 5-10 seconds; inspect tip
Repeat passes as needed until point is sharp and symmetric
Power off motor before removing pin vise from collet

Tip Geometry Reference

Tungsten Ø	Grind angle	Use case
1/16"	15-20°	Thin gauge GTAW, ≤1.5mm carbon/stainless
3/32"	30°	General purpose GTAW carbon/stainless (UA46 standard)
1/8"	30°	Heavy section, higher amperage
5/32"+	30°+	Specialty work — instructor confirmation required

Prohibitions

Never operate this grinder for any material other than tungsten electrodes — contamination of the wheel ruins it AND can transfer to weld pool
Never grind without P100 respirator — universal rule, not thoriated-specific
Never wear loose gloves, neckties, rings, bracelets, or jewelry around the rotating wheel (per manufacturer §4 SAFETY); tight-fit gloves are operator preference

Emergency Stop

Emergency Response Push rocker switch to OFF (the LED will extinguish). Wait minimum 30 seconds for wheel to fully stop (no braking — coast-down only). If switch is unreachable or unresponsive, unplug the cord at the wall outlet. If the unit appears to draw power but won't run, the integrated circuit breaker may have tripped — power off, unplug, allow 5 minutes, then reset the breaker before restart. DO NOT contact the wheel while spinning or coasting down — even at 1,700 RPM, the diamond wheel will cut tungsten or skin.

Scenario	Immediate response	Notify
Wheel disintegration / shrapnel	Power off; clear area; do not approach until wheel fully stopped	Instructor immediately
Cord damage during operation	Do not touch; power off at wall breaker if accessible	Instructor immediately
Inhalation symptoms (cough, throat irritation)	Leave area; remove respirator only outside grinding zone	Instructor + first aid
Fire (dust accumulation ignition)	Class ABC extinguisher; never water	Instructor + 911 if not contained

Power Isolation

Cord-and-Plug Control Before servicing, cleaning, or accessory change — unplug the unit and maintain exclusive control of the plug. Per CSA Z460-20 cl. 4.3.5.

Power switch OFF; wait for wheel to fully stop
Unplug cord at wall outlet
Apply personal lock+tag at plug if service >5 minutes

Post-Use

Power off motor; wait for wheel to stop completely
Disconnect cord from outlet
Open dust shield; inspect for buildup
Empty dust receptacle into labelled thoriated-waste container if >50% full
Wipe machine exterior with damp cloth — NEVER compressed air
Return collet to storage; pin vise to tool tray

Related Resources

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ELIM

Phase out thoriated tungsten where weld quality permits. At UA46, current WPS specifications frequently require EWTh-2 (2% Thoriated), restricting substitution. Phase-out remains aspirational, not currently implementable shop-wide.

SUB

Where WPS allows: use Diamond Ground TRI-MIX (WS2), 2% Lanthanated, or CRYO-T (note: CRYO-T is also radioactive — cryogenically treated thoriated). For WPS-mandated EWTh-2, substitution is not an option.

ENG

Piranha III's 100% containment housing (closed during operation); sliding dust shield (adjustable per angle); bottom receptacle captures spent dust; three-prong grounded cord; integrated circuit breaker; LED power indicator.

ADM

Authorized-operators-only; pre-use inspection; no-shared-grinder-with-other-materials rule (dedicated tungsten only); tungsten-type-segregation discipline; recommended pin vise use for finger-heat protection (manual allows either rotation method); maximum 60° angle limit per manufacturer; periodic dust receptacle vacuum/emptying (PM schedule).

PPE

CSA Z94.3 safety glasses + P100 half-face respirator mandatory for all grinding sessions (thoriated or not — universal rule); hearing protection optional; long hair contained.

Before you sign off on this machine

On the next page you will confirm you have:

Read this entire SOP
Received instructor demonstration of the procedure
Demonstrated competent operation to the trainer
Understood the prohibitions and the emergency stop
Had the opportunity to ask questions

If you are unsure about any step or any control on this machine, stop and ask the instructor before you sign off.

Sign off on the Piranha III Tungsten Grinder →

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SOP-EQ-006

Confirm training — scan to sign off Scan this code to record your acknowledgment of this SOP. Required before independent operation.