REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues	$ 248,026	$ 228,618	$ 446,681	$ 428,218
Non-Destructive Evaluation and Testing Services
Disaggregation of Revenue [Line Items]
Revenues	100,637	90,113	185,081	171,123
Repair and Maintenance Services
Disaggregation of Revenue [Line Items]
Revenues	117,105	112,875	208,393	211,883
Heat Treating
Disaggregation of Revenue [Line Items]
Revenues	22,071	17,707	38,632	31,298
Other
Disaggregation of Revenue [Line Items]
Revenues	8,213	7,923	14,575	13,914
IHT
Disaggregation of Revenue [Line Items]
Revenues	130,396	113,234	236,611	212,682
IHT | Non-Destructive Evaluation and Testing Services
Disaggregation of Revenue [Line Items]
Revenues	100,637	90,113	185,081	171,123
IHT | Repair and Maintenance Services
Disaggregation of Revenue [Line Items]
Revenues	51	2	52	147
IHT | Heat Treating
Disaggregation of Revenue [Line Items]
Revenues	21,922	17,459	38,294	30,943
IHT | Other
Disaggregation of Revenue [Line Items]
Revenues	7,786	5,660	13,184	10,469
MS
Disaggregation of Revenue [Line Items]
Revenues	117,630	115,384	210,070	215,536
MS | Non-Destructive Evaluation and Testing Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
MS | Repair and Maintenance Services
Disaggregation of Revenue [Line Items]
Revenues	117,054	112,873	208,341	211,736
MS | Heat Treating
Disaggregation of Revenue [Line Items]
Revenues	149	248	338	355
MS | Other
Disaggregation of Revenue [Line Items]
Revenues	427	2,263	1,391	3,445
United States
Disaggregation of Revenue [Line Items]
Revenues	184,286	166,540	341,660	319,417
United States | IHT
Disaggregation of Revenue [Line Items]
Revenues	111,987	98,712	208,384	187,287
United States | MS
Disaggregation of Revenue [Line Items]
Revenues	72,299	67,828	133,276	132,130
Canada
Disaggregation of Revenue [Line Items]
Revenues	25,424	22,798	37,631	35,187
Canada | IHT
Disaggregation of Revenue [Line Items]
Revenues	15,112	11,499	22,224	19,220
Canada | MS
Disaggregation of Revenue [Line Items]
Revenues	10,312	11,299	15,407	15,967
Other Countries
Disaggregation of Revenue [Line Items]
Revenues	38,316	39,280	67,390	73,614
Other Countries | IHT
Disaggregation of Revenue [Line Items]
Revenues	3,297	3,023	6,003	6,175
Other Countries | MS
Disaggregation of Revenue [Line Items]
Revenues	$ 35,019	$ 36,257	$ 61,387	$ 67,439