In January 2025 a US manufacturer of industrial sight flow indicators asked us to cast its bronze bodies. We cast them in 85-5-5-5 leaded red brass, machined the NPT threads, worked through a drawing revision and a full tooling change, and shipped DDP to the customer's warehouse. In the following 16 months the customer placed ten purchase orders with us.
The customer's requirements
- Parts: sight flow indicator bodies and matching ring nuts, pressure-rated parts that let operators see fluid moving through a pipeline.
- Material: 85-5-5-5 (C83600) leaded red brass; the customer was open to alternatives.
- Volume: about 500 to 800 pieces per year per part number.
- Scope: first rough castings only, then rough castings plus finished machining with threads.
- Marking cast on the part: brand name, country of origin, and a 150 PSIG / 400°F maximum rating.
Two questions we asked before quoting
Oil or water? The service fluid decides whether a cheaper alternative alloy is acceptable. For a pressure-rated part we kept 85-5-5-5 as the default.
Can you send a 3D model? Bronze castings are priced mostly by weight. A STEP file lets us calculate the poured weight instead of estimating it from a 2D print.
We also learned the customer's numbering: parts ending in -9xx were rough castings and parts ending in -0xx were the finished parts machined from them. Quoting both levels as separate lines let the customer compare buying castings versus finished parts.
How the project ran
| Step | What we did |
|---|---|
| Quotation | Rough casting and finished part priced separately, based on weight from the 3D models |
| Samples | 2 pieces per part number with machined threads, about 30 days after deposit |
| Engineering questions | Short screen recordings on the 3D model to ask about unclear dimensions, faster than long emails across time zones |
| Tooling | Patterns and core boxes for each body |
| Machining | NPT threads and sealing faces machined by us |
| Inspection | Photos, an assembly video and an inspection report before every shipment |
Problem 1: a drawing revision after tooling had started
Three weeks into pattern making, the customer's engineers found an error in their own drawings: a hex had been dimensioned across flats instead of across corners. The corrected parts were noticeably heavier.
We stopped the tooling, rebuilt the affected patterns and charged only the modification cost. Our own mistake was that we did not warn the customer at that moment that the heavier design would also raise the unit price. We explained the weight increase openly when we re-quoted and invited them to weigh the samples. Since then, when a drawing change affects weight, we re-quote before we continue.
Problem 2: cast-in text that was hard to read
On the first samples the cast-in text was too small to read clearly. Together with the customer we:
- shortened the rating text to "150 PSIG MAX" and "400°F MAX";
- placed the brand name above the rating instead of above the flow arrow;
- reduced the rating text from 8 pt to 7 pt so the brand name and country of origin stay larger;
- added the degree symbol and chamfered the edges.
The revised samples were approved and mass production started the same week.
Problem 3: shipping heavy bronze to the US
The first order weighed about 1,200 kg. We shipped by sea directly from China and quoted DDP (delivered duty paid): ocean freight, customs clearance, import duty and trucking to the warehouse in one price. When the customer compared it with an ocean-freight-only rate, we broke down what the DDP price covered so there were no surprises at the port.
When we got it wrong
On one shipment the freight forwarder collected the wrong cartons: the 3/8 in NPT version was shipped under the part number of the 1/2 in NPT version, and one line was three pieces short. We traced the cause, corrected the paperwork, sent the correct parts and the missing pieces with the next order, and gave a discount on that part number. We now check part numbers against the drawing at carton level before pickup.
Results
- First order shipped in August 2025; on a later shipment the customer told us they were very happy with the castings.
- Ten purchase orders in 16 months, including a bronze reorder finished ahead of schedule.
- The customer later asked whether we could also pour carbon steel and iron. Through partner foundries in our network we now also supply them steel valve castings and ductile iron parts.
Frequently Asked Questions
What bronze alloy is used for sight flow indicator and valve bodies?
We use 85-5-5-5 (C83600) leaded red brass as the default for pressure-rated bodies and can review alternatives once we know the service fluid and pressure.
Do you quote rough castings and machined parts separately?
Yes. We quote the rough casting and the finished machined part as separate lines, so you can decide whether to machine in-house.
How long do bronze casting samples take?
About 30 days after deposit for new tooling and samples. Chinese New Year can add three to four weeks if it falls inside the schedule.
Can pressure ratings and lettering be cast into the part?
Yes. Small cast-in text needs enough size and depth; we send photos of a test layout for approval before mass production.
Can you ship DDP to the United States?
Yes. We can quote sea freight door to door including customs clearance and import duty, so the approved price is the delivered price.
Written by the Gaton Brass team, Zhongshan, Guangdong, China. Published 2026-10-07. Customer names and drawings are withheld at the customer's request.