DISTRIBUTOR-FIRST SUPPLY PARTNER · SINCE 1999 BRAND · DK-LOK
The engineered drop-in for Swagelok and Parker A-LOK instrumentation lines.
Code-rated. Drop-in ready.
DK-LOK was established in 1986 in Gimhae, South Korea, and has grown into one of the few instrumentation fitting manufacturers in the world recognized for technical capability comparable to Swagelok. The product line covers two-ferrule compression tube fittings, ball valves, bellows valves, tubing, and tools — all manufactured to precise dimensional standards and exported to more than 40 countries.
The engineering basis that separates DK-LOK from generic alternatives is the ASME B31.3 / B31.1 pressure calculation using an S-value of 20,000 psi. That gives engineers an auditable code basis for high-purity and process lines — the kind of documentation an EPC contractor or plant inspector actually needs. Dimensional compatibility with Swagelok and Parker A-LOK/CPI is engineered in, so the fitting drops into an existing system without a redesign or engineering change order.
DK-LOK holds a wide range of international quality and classification certifications including ISO 9001, ISO 14001, ASME nuclear stamps (N, NPT, NS — second globally to achieve all three, first in Korea), API 6D, API Q1, and PED. That certification depth puts DK-LOK on the approved-vendor lists for oil and gas, nuclear, marine, and high-purity process industries worldwide.
SPC carries DK-LOK as an authorized distributor, so the part number you spec is the part that ships — no gray-market substitutions, with direct pricing behind aggregated demand through the distribution network.
DK-LOK's Swagelok and Parker A-LOK / CPI dimensional compatibility means high-count instrumentation projects can reduce fitting cost without an engineering change order.
Every fitting's pressure rating traces to ASME B31.3 / B31.1 calculation — not a catalog maximum.
Oil & Gas / Energy → Instrumentation and process fittings on wellhead, pipeline, and refinery skids. 
Chemical & Petrochemical → High-purity 316 SS fittings for corrosive and high-pressure chemical process lines. 
Pharmaceutical, Medical Device & Laboratory → Ultra-high-purity tube fittings for sterile process and laboratory gas distribution. 
Electronics & Semiconductor → Clean fittings for high-purity gas distribution in semiconductor fabrication. 
Power Generation → Instrumentation fittings for steam and process measurement in power plant systems. 
Marine & Shipbuilding → ABS/DNV/LR-approved fittings for offshore and shipboard instrumentation systems. DK-LOK two-ferrule fittings are dimensionally compatible with both. Cross the installed part number by tube OD (fractional 1/8"–2" or metric 3–50 mm) and material (316 SS standard; 304 SS available). No redesign is required — the fitting seats into the existing nut and back ferrule.
All ratings are calculated to ASME B31.3 / B31.1 at S-value 20,000 psi. Confirm the MAWP of the line and match to the DK-LOK pressure table for the tube OD and wall thickness. For code-sensitive projects, the calculation basis is available for engineering review.
DK-LOK holds ASME nuclear stamps (N/NPT/NS), API 6D/Q1, PED, and major marine classification society approvals. Specify the required certification at order time to ensure the correct stamped or certified material trace documentation ships with the order.
316 SS covers −425°F to +1200°F for the full range from cryogenic to high-temperature process. For oxidizing or corrosive high-temperature service, confirm compatibility with the process fluid — DK-LOK also offers specialized alloy options on request (Monel, Hastelloy, Alloy 400/600/625/825, super duplex, and titanium).
Tell us the spec and the account and we will come back with the right line, sourced through the distribution network.
—. We reply within one business day with pricing, lead-time, and configured parts.