Pressure housings: Manufacturing

Pressure housings: Simple in concept and nuanced with details.

National K Works expertly manufactures and tests pressure housings to your exact specifications and needs. We are precision specialists who engineer, manufacture, and test high pressure high temperature solutions. Our products are known for their exceptional reliability, and our well-known service is highly customer-focused in every detail. We have a strong record of demonstrated competency and expertise. Contact us today to ask any questions you may have or discuss the details of your pressure housing manufacturing and testing needs.

Custom Design

We have the manufacturing and engineering expertise to execute your downhole pressure housing design and manufacturing to your exact specifications. All of our pressure housing work is custom to our clients' designs and needs.

Why Choose National K Works for Custom Pressure Housing Manufacturing?

We are driven by our core values to deliver the highest quality of work and service. Our clients usually work with us on a long-term, repeat basis, and our clientele includes some of the world's largest corporations that rely on our exceptional performance and proprietary manufacturing solutions. Our clients work with us again and again for their precision pressure housing projects for a number of reasons, including our:

  • Quality
  • Reliability
  • Performance
  • Collaboration
  • Focus on Design & Solutions
  • Attention to Detail
  • Superior Design
  • Master Craftsmanship

For more information, read our client testimonials here. Or, check out our case studies here.

Synonyms for Pressure Housings

Pressure barrel, Instrument Barrel, Pressure vessel, Sonde housing

Function of Pressure Housings

A down hole pressure housing is a precision tube of high strength material with sealed ends that houses and protects downhole instruments from wellbore fluid and external hydrostatic forces.

Critical manufacturing components

Concentricity between ID/OD (uniformity of wall thickness), Precision of ID and OD size and shape, Straightness, Precision of machined end closures, Welding, Material properties, Pressure testing


Common materials are 17-4 stainless, Nitronic 50, Inconel 718, Copper Beryllium, Copper Nickel and Titanium Alloys.

Tube source

Most pressure housings are made from bar material that is deephole drilled to produce a precision tube. Mill produced tubing requires large volume minimum orders and consequently has high initial costs. National K Works specializes in economically producing precision tube from bar material via Cobore. Typical OD sizes range from 0.75" (19mm) for slim hole production logging tools to 5.0" (127mm) for ultra-high pressure deep water open hole logging tools. Lengths have ranged from 6" (152mm) to 216" (5.5m). Longer lengths are easily manufactured.


Concentricity (uniformity of wall thickness) is one of the most critical yet under toleranced features of a pressure housing. National K Works specializes in producing tight concentricity tolerances between the ID and OD. Our standard tolerance is 0.010" (0.25mm) maximum positional tolerance between the ID and OD (+/-0.005" (0.13mm) maximum wall thickness tolerance) along the entire length of the pressure housing.


National K Works specializes in machining precision threads, blunt starts on threads, critical seal bores, fluid porting (radial and axial) features, internal cavity features for latching and orienting chassis and connectors, internal and external tool joint orientation features, external identification bands for depth correlation of sensors, deep bore internal chambers for seal ramps and connector guidance.


Welding is performed on National K Works' proprietary welding machines that have program controlled variables pulled from a library of welding procedures. Joints are not welded by hand. Weld joint integrity is verified during pressure testing. Thin cross section welds like those found on internal gas chambers are verified with Helium leak testing.


Housings are straightened prior to machining end features to ensure perpendicularity to centerline. Critical fits between chassis and bore are verified with a functional "drift" specimen that replicates the chassis and its fit to the pressure housing.

Positional tolerances

When critical multi-bore sealing configurations are inaccessible with conventional measuring tools (such as those on formation testers), National K Works verifies the position of the bores using National K Works designed gage fixtures that replicate the actual functions of the mating parts.

Pressure Testing for Downhole Pressure Housings

Pressure testing verifies the mechanical integrity of the pressure housing and the seal integrity of all the connections on a pressure housing. It is a crucial risk management test to avoid failures in an actual well. National K Works pressure tests to 35,000 psi (241MPa) maximum at ambient temperature. We have made, and have in inventory, seal testing fixtures for over 400 different tool joints used across the industry.

Contact Us for Pressure Housing Manufacturing and Testing

If you are looking for an expert and precision company to manufacture and test pressure housings, don't hesitate to contact us today to ask any questions you may have or discuss the details of your pressure housing manufacturing and testing needs.

Verification of seal bore surface finish during pressure housing manufacturing process
Verification of seal bore surface finish on an Inconel housing. The external knurled bands allow heavy torque loading of the threads for high shock and vibration encountered in coil tubing drilling.
Long cased hole pressure housing
Long cased hole pressure housing with welded upper head
Precision tube blanks for pressure housings
Precision tube blanks prior to the subsequent honing operation that improves bore finish
Both ends of a long Inconel pressure housing
Example of both ends of a long Inconel pressure housing. The housing on the right has two internal EDM'ed (electrical discharge machined) features. The deeper feature (visible at 6 o'clock) is for latching and orientating the chassis. The internal keyway evident in the upper section (visible at 12 o'clock) is cut through the length of threads and is for tool joint orientation. The housing on the left has the mating external tool joint orientation key (visible at 12 o'clock).
Internal keyway for tool joint orientation of downhole pressure housings
Example of internal keyway for tool joint orientation
Radial pressure port on pressure housing
Radial pressure port with sealing surfaces and anchoring feature
Milling features on a centralizer housing
Milling features on a centralizer housing on 120" long 4 axis milling machine
Verification of thread profile on pressure housings
Verification of thread profile
Blunt start on external thread of pressure housings
Blunt start on external left hand thread
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