Lincoln Electric IM467-B manual Table B.2 Typical Current RANGES1 for Tungsten ELECTRODES2

B-18						OPERATION								B-18
						TABLE B.2
			TYPICAL CURRENT RANGES(1) FOR TUNGSTEN ELECTRODES(2)
							AC			Approximate Argon
		DCEN (-)		DCEP (+)	Unbalanced Wave			Balanced Wave		Gas Flow Rate
											C.F.H. (l/min)
Tungsten						1%, 2%			1%, 2%
Electrode		1%, 2%		1%, 2%		Thoriated			Thoriated					TIG Torch
Diameter		Thoriated		Thoriated	Pure	Tungsten		Pure	Tungsten			Stainless		Nozzle
in. (mm)		Tungsten		Tungsten	Tungsten	Zirconated		Tungsten	Zirconiated	Aluminum		Steel		Size (4), (5)
.010	(.25)	2-15		(3)	2-15	2-15		2-15	—	3-8	(2-4)	3-8	(2-4)	4,5,6
0.020	(.50)	5-20		(3)	5-15	5-20		10-20	5-20	5-10	(3-5)	5-10	(3-5)
0.040	(1.0)	15-80		(3)	10-60	15-80		20-30	20-60	5-10	(3-5)	5-10	(3-5)
1/16	(1.6)	70-150		10-20	50-100	70-150		30-80	60-120	5-10	(3-5)	9-13	(4-6)	5,6
3/32	(2.4)	150-250		15-30	100-160	140-235		60-130	100-180	13-17	(6-8)	11-15	(5-7)	6,7,8
1/8	(3.2)	250-400		25-40	150-210	225-325		100-180	160-250	15-23	(7-11)	11-15	(5-7)
5/32	(4.0)	400-500		40-55	200-275	300-400		100-240	200-320	21-25	(10-12)	13-17	(6-8)	8,10
3/16	(4.8)	500-750		55-80	250-350	400-500		190-300	290-390	23-27	(11-13)	18-22	(8-10)
1/4	(6.4)	750-1000		80-125	325-450	500-630		250-400	340-525	28-32	(13-15)	23-27	(11-13)

(1)When used with argon gas. The current ranges shown must be reduced when using argon/helium or pure helium shielding gases.

(2)Tungsten electrodes are classified as follows by the American Welding Society (AWS):

Pure	EWP
1% Thoriated	EWTh-1
2% Thoriated	EWTh-2

Though not yet recognized by the AWS, Ceriated Tungsten is now widely accepted as a substitute for 2% Thoriated Tungsten in AC and DC applications.

(3)DCEP is not commonly used in these sizes.

(4)TIG torch nozzle “sizes” are in multiples of 1/16ths of an inch:

# 4	= 1/4 in.	(6mm)
# 5	= 5/16 in.	(8mm)
# 6	= 3/8 in.	(10mm)
# 7	= 7/16 in.	(11mm)
#8 = 1/2 in.		(12.5mm)
#10 = 5/8 in.		(16mm)

(5)TIG torch nozzles are typically made from alumina ceramic. Special applications may require lava nozzles, which are less prone to breakage, but cannot withstand high temperatures and high duty cycles. Currents above 350 amps require metal nozzles on water cooled torches.

SQUARE WAVE TIG 355