Custom Drilling and Tapping

Guidelines for Custom Drilling and Tapping for Conduits: Nema 7 Hazardous Location Enclosures

Custom Drilling and tapping in Nema 7/9 explosion proof enclosures is not a task that should be left up to just any machine shop or done in the field with hand tools. Always check to see if the shop has a hazardous location UL NNY certificate and is familiar with the specific UL code for drilling the explosion-proof box. If the box is not drilled with the proper allocated spacing not only can the warranty and UL listed be void but the integrity of the enclosure is in jeopardy. Should an explosion happen the enclosure it may not contain the explosion causing the enclosure to fail and igniting the atmosphere.

Always have approval drawings done with the exact placement of the entries. All of our enclosures have engineered CAD drawings done for our customers to ensure that the placement of the entries is exactly what our customer wants. Explosion-proof enclosures should always be handled by competent personnel. Handling the enclosure properly to maintain the quality of the flame path is crucial. Our ISO-certified step by step producers ensure the flange flame path is
protected during the entire machining process. We have special build padded carts along with our overhead cranes to move the enclosure to and from the CNC machine or drill press. Should a single hair line scratch happen across the flange it can cause failure in the enclosure during an explosion and allow a flame to escape the enclosure igniting the atmosphere.

If the box is not drilled with the proper allocated spacing not only can the warranty and UL listed be void but the integrity of the enclosure is in jeopardy.

Tapping the conduit entries should always be handled by a qualified and trained machinist. We use lasers scanning & measuring tools to ensure all drilled holes (both inside and out) are aligned to components and according to drawings or customer specifications. Our calibrated thread gauges checks every thread after machining to ensure the quality of the threads. Our quality controls department assures that dimensions are within specified tolerances, edges are free from sharp edges and threads are complete.

Cleanliness of the Nema 7 explosion-proof enclosure is crucial. During the machining process oil is used to keep the drill bit cool. One the enclosure is done being machined it is covered in oil, dust, and shavings. The box must be cleaned properly to ensure all oil is removed from the pores and there is not metal shavings left inside the enclosure and even more importantly on the flame path 7 gasket. Our ISO 9001 custom drilling and tapping conduit entries procedures exceed any other manufacture in the industry’s requirements. We are a trusted UL listed NNY company that excels to give you the best quality products.

Quality is never sacrificed for speed but we know that getting your product quickly is important. Our standard lead time is 5 working days but 3-day, one-day quick ship is available with an expedite fee. 

Questions to think about when reviewing your existing suppliers:

How does a late shipment affect you?

• Does it result in production delays?
• Does it result in unbudgeted overtime?
• Does it result in other expedite fees or expedited shipping costs?

What’s the true cost of quality to you?

• Does poor quality delay your production schedule?
• Does it consume other resources, such as engineering, that could be working on more productive tasks?
• How are future sales affected by a quality failure in the field?

Won’t it cost more to outsource than to do it internally?

• Do you have the proper equipment to machine the part internally?
• Do you have hazardous location UL listings?
• How is the quality with the internal process?
• Does the quality cause more problems in subsequent operations?
• If you consider lost labor time at all stages, what’s the true cost of the part?
• Can your existing labor be better utilized doing something else?

What other value-added services do you get?

• Are critical dimensions nominal, or just in tolerance?
• Do you get suggestions on cost savings?
• Do you get print or tolerance errors pointed out, before the parts are made?
• Do you get help during initial design stages, to reduce cost and time?