A real Chinese reactor factory answers nine specific questions in writing within one working day — design pressure in MPa, glass lining thickness in mm, high-voltage test voltage in kV, furnace size, welding procedure, invoicing entity and warranty terms — and a trading office usually cannot. Price is not the tell: a 3,000 L jacketed glass-lined reactor with a mechanical seal lands at USD 8,000–14,000 ex-works whether you buy from a factory or a reseller. What changes is who carries the warranty and who signs the quality certificate.
1. Being a trader is not the problem
A reseller is sometimes the correct answer. A 50 L vessel, one shipment that combines a reactor, a storage tank and a condenser, an English-speaking interface across three workshops, a single contract with one point of payment — these are real services, and somebody has to be paid for them. Paying a reseller's margin for a reseller's service is not a mistake.
The mistake is not knowing which party you are dealing with. Buyers get hurt when they expect factory-direct accountability and receive reseller recovery, or when they assume the warranty is backed by the shop that fired the lining. Nobody objects to a trading company. Buyers object to a trading company answering "we are the factory" and then quoting someone else's vessel.
So do not ask "are you a factory?". Anyone can say yes. Ask questions whose answers can only come from a shop floor, and check the documents that carry serial numbers.
2. Nine questions, and the answer that gives it away
Question 1 — What is the design pressure, inner vessel and jacket, in MPa?
Ask for both figures plus the design temperature in °C. A factory engineer gives you two numbers and then asks what you are reacting, in what medium and at what jacket temperature, because jacket type and sealing arrangement change with the duty. A trading office replies with a model number and a catalogue figure. Design pressure and design temperature must appear on the numbered specification confirmation sheet you approve, not only in an email.
Question 2 — Where is the shell welded, and can I see the welding procedure?
Ask for the welding procedure specification and the welder qualification records for the shell and jacket seams, and ask whether shell welding is done in-house or subcontracted. A factory names its welders, its procedure numbers and how jacket seams are examined. A reseller forwards a scanned page with somebody else's drawing title block on it. The title block names the party that actually manufactured the vessel — read it.
Question 3 — Which furnace fires the glass lining, and what is the largest vessel it takes?
Glass lining is fired, and the useful furnace diameter and depth cap the vessel size that can be supplied. Ask how many firing cycles a vessel of your size needs. A factory states the furnace dimensions. A reseller answers with the largest unit it has ever sold, which is a different number. If your enquiry is at the large end of the range, this one answer decides whether the supplier can make the vessel at all.
Question 4 — At what kV is the lining high-voltage tested?
Every glass-lined vessel is high-voltage tested to find pinholes in the lining, so ask for the test voltage in kV and for a signed record showing the vessel serial number and the date, from a vessel of comparable size. A factory pulls the file. A reseller cannot, or sends an unsigned template. Then ask what happens to a lining that fails: is the defect ground out and patched, or is the vessel stripped and re-fired? The repair route should be described without hesitation.
Question 5 — What is the lining thickness in mm, and how do you measure it?
The answer is a range plus a method — a thickness gauge read at defined points, not a nominal figure in a brochure. "Standard thickness" is not an answer. Ask also for the thermal shock limits the lining is designed to: cold shock up to 110 °C and heat shock up to 120 °C are the figures that govern how you charge a hot vessel.
Then ask the honest question: what is this lining not suitable for? Hydrofluoric acid and fluoride-bearing media are out. Phosphoric acid at 30 % and above, above 180 °C, is out. Strong alkali above pH 12 at 100 °C is out. A supplier who does not raise those exclusions before you order has not read your process description.
Question 6 — Which mill does the plate come from, and will you supply mill certificates?
Shell material runs from carbon steel through 304/316L to titanium, duplex stainless, Hastelloy and clad plate. Ask for material certificates traceable by heat number to the plate used in your vessel, and ask for the shell thickness on your drawing rather than for the model series. A factory has those certificates in the job file. A reseller has to request them from a third party, and what arrives is often a generic sheet without your heat number on it.
Question 7 — Who signs the specification sheet I approve?
Internal dimensions, heat-transfer area, agitator power, nozzle layout and unit weight follow your duty, not the model designation. Ask who drafts the numbered specification confirmation sheet, whether the agitator, seal and drive are specified as one system, and whose name countersigns it. A factory sends a document with a drawing number, a revision and an engineer's signature. A trading office sends your own enquiry back as a quotation.
Question 8 — What is the heaviest lift and the largest diameter in your shop?
Crane capacity in tonnes, maximum shell diameter and bay door height decide whether the vessel can physically be built where the quotation says it will be built. Ask for the workshop address and a live video walk-through with the QC manager, not a factory film recorded years ago. Then ask for the nameplate and serial number to be photographed at three fixed stages: after welding, after lining, and at final inspection before crating.
Question 9 — Who invoices me, and who honours the warranty?
Ask for the legal entity name that will appear on the invoice, the payment schedule in writing, the warranty period, and precisely what is excluded from it. Ask who pays for third-party pre-shipment inspection by SGS, BV or TÜV, and how the inspection scope is agreed. Then ask what happens in practice if the lining fails in the first year: who travels to site, at whose cost, and whether the repair or the vessel is warranted. The answer separates the party that controls the shop from the party that will phone the shop on your behalf.
3. What you can verify from your desk
Check the business licence scope on China's national enterprise credit information system: legal entity name, registered capital, registered scope of business, and whether the registered address matches the workshop address you were given. Check the special equipment manufacturing licence covering pressure vessels and the export registration. Then follow the paperwork trail — certificate of origin, third-party inspection report, material certificates with heat numbers, and the numbered specification sheet you approved.
No single document proves a factory. The full set, with serial numbers that match the vessel standing in front of you, does.
4. When a trader is the right choice
Small volumes, mixed packages, multi-factory consolidation, an English-speaking interface, or a buyer who needs one contract rather than five: in those cases a reseller earns their margin and a factory-direct relationship costs you more in time than it saves. The rule is simple. Buy a reseller's service at a reseller's price, and buy factory-direct when you are paying for the party that fires the lining. Whoever you choose, write down which one they are on the quotation.
We are a sourcing office in Zibo, Shandong, not a factory. We do not own a plant and we do not present one as ours. What we sell is specification, audit, inspection and accountability through the build and after the invoice is paid — and we will tell you, in writing, which workshop is making your vessel and who signs its test records.
5. What to do next
- Send all nine questions in one email, in writing, and ask for documents rather than assurances.
- Require a numbered specification confirmation sheet carrying design pressure in MPa, design temperature in °C, lining thickness in mm and high-voltage test voltage in kV, and approve it before fabrication starts.
- Book a live video walk-through with the QC manager, and request stage photographs showing the serial number.
- Move the answers on warranty, invoicing entity, inspection scope and spare parts into the purchase order, not the email thread.
- Budget USD 8,000–14,000 ex-works for a 3,000 L jacketed glass-lined reactor with a mechanical seal, and treat a quotation well below that as a difference in specification, not a bargain.