Buying a 25 m³ Slag Pot: Material, Inspection and Delivery Checks

A 25 m³ slag pot isn't a catalog item. Same nominal volume, and you can still end up with two very different builds. Slag chemistry pushes one set of choices. The heat-and-cool cycle pushes another. Then there's how the pot gets cleaned out, and what it has to bolt onto at the plant. Get all of that on the table before anyone starts talking about material.

Five stages follow, material through delivery. At each one, a handful of points need settling before the order goes out. Purchasing, production and maintenance all have a stake in them. Use the list as a checklist when you draft the technical agreement.

1. Material: let the duty pick the grade, not the volume

Volume tells you nothing about what the pot should be made of. Start with the slag itself. Then thermal cycling, cleaning practice, the geometry, and what the pot has to perform at. All of it goes into the review.

Grade settled? Then the chemistry gets checked heat by heat. Carbon, silicon, manganese, sulfur, phosphorus, each one against the agreed spec. If the composition is adjusted, that heat may need re-sampling or re-testing. Keep that paperwork too.

One more point on traceability. The heat number on the material certificate has to lead back to a specific pot. Without that link, a test result proves nothing about the casting standing in front of you.

Ask three things: does the grade match the duty? Are the composition records complete? And can you walk from heat number to pot number without a gap?

2. Pouring: watch the heavy sections and the thickness transitions

Before the pour, the feeding and solidification plan gets reviewed against the drawing. On a slag pot, that conversation is mostly about three places. The trunnion root, where the trunnion is cast integral with the body. The bottom. And every point where the wall steps from thick to thin.

During the pour, tap temperature, pouring rate and slag carry-over go by the approved practice. Pours don't always cooperate. If one gets interrupted, or anything else drifts off plan, write down what actually happened. Later, when you assess the casting, that note is what you'll be working from.

Afterwards comes solidification, cooling, shakeout and cleaning, all to the process sheet. Internal soundness gets judged by whichever method was agreed up front.

Three questions: were the critical sections reviewed? Is every deviation written down? And how, exactly, is internal quality verified?

3. Heat treatment: read the charts, not just the certificate

A slag pot gets heated and cooled over and over in service. Heat treatment has two jobs. Bring residual stress down, and get the steel to the properties you specified.

On thick sections, ask how the holding time was worked out. A setpoint on the furnace controller is not the same thing as the middle of a heavy section reaching temperature. Two different numbers, and only one of them matters here.

Read the charging record, the multi-point temperature charts and the mechanical test results together. One without the others won't tell you much.

Ask: are the parameters defined? How is soak controlled on the heavy parts? And is there test data behind the properties, or just a line on a certificate?

4. Inspection: agree method, extent and acceptance before the first cut

A 25 m³ pot gets signed off on three things. What it looks like, what it measures, and what the NDT says.

MT and UT do different jobs. Magnetic particle testing finds surface and near-surface discontinuities in ferromagnetic steel. Ultrasonic testing looks for internal ones, where the geometry lets sound through. Don't swap one for the other. Which method covers which area should come off the drawing and the technical requirements, not out of habit.

Critical areas get defined before manufacturing starts. Trunnion roots first among them. The technical agreement should name the standard, the edition and the acceptance level. A line like "Grade 1 NDT" or "NDT passed" doesn't answer the only question that matters: does this pot meet the order.

Weld repair? Then there's a paper trail. Approved procedure. Repair record. Re-test results. And the release, signed by whoever agreed to it.

Check: are the test areas defined? Do both sides mean the same thing by the acceptance standard? Are re-tests and releases closed out?

5. Shipping: match the interfaces and the transport

Before dispatch, trunnion dimensions, support positions and tilting connection points get checked against the equipment on site. Replacing an old pot? Find out first whether the site equipment has been modified since the original was built. Skip that step and the pot arrives matching a drawing that no longer describes the plant.

For transport, confirm weight, center of gravity, how the pot is supported and restrained, and protect the machined surfaces, trunnions especially.

Check crane capacity and rigging at the receiving end too, and keep loading photos and transport documents keyed to the pot number.

Check: do the connection dimensions match? Is the transport plan workable? And can the site receive and lift the pot?

On arrival: tie the paperwork to the pot

Use the pot number as the thread and work through:

·chemical and mechanical results for the heat

·heat treatment records

·dimensional and NDT reports

·weld repair approvals and re-test records, where applicable

·the transport condition record and the operating instructions

Then look the pot over, and follow the instructions for pre-commissioning checks and any drying or preheating.

Linking the physical pot, its quality records and its operating information pays off later, at acceptance, in service and at maintenance.

Custom slag pots from Xintengfei

Henan Xintengfei Cast Steel casts, heat treats, machines and tests large custom steel castings. Projects start with a review against the customer's drawing, material specification and technical requirements.

We use casting simulation, in-house chemical and mechanical testing, and NDT to support quality control, and we set out the manufacturing, inspection and delivery points per order.

Buying or replacing a 25 m³ slag pot? Send the drawing, the material, how many you need, the operating conditions and the inspection requirements. We'll come back with how the build and delivery would run.

FAQ

What should I send you for a 25 m³ slag pot quote? The drawing and its revision, material specification, quantity, slag type, the heating and cooling cycle, and how the pot is cleaned. Trunnion, support and tilting connection dimensions as well. Add the NDT standard, the documents you expect at handover, and the transport and lifting conditions on site.

Can two pots of the same volume use the same material? Not automatically. It depends on duty, geometry and the properties required. For a replacement, check what the original was designed to first. Any change in material should go through a technical review and be signed off.

Why the focus on the trunnion root? It carries the load, and it's where the section changes. On an integrally cast trunnion, feeding of that area has to be addressed in the process review, and the area is then inspected to the agreed extent and standard.

What should I look for in an NDT report? Pot number, method, standard and edition, extent of testing, acceptance level, and the conclusion. If there was a weld repair, the approval and re-test records as well.

What has to happen before a new pot goes into service? Four steps, in this order. Match the documents to the pot number. Inspect the pot as it arrived. Confirm the interfaces actually fit. Then run the pre-service checks, plus any drying or preheating the instructions call for.