# 347H Pipe for High-Temperature Service: Data Needed Before Quoting

Canonical: https://jundapipe.com/en-CA/blog/347h-pipe-high-temperature-enquiry

Prepare a 347H pipe enquiry with design temperature, duration, cycling, material condition and inspection requirements instead of a temperature label alone.

A useful 347H pipe enquiry states the design temperature and pressure, operating duration, thermal cycling, process environment and governing code. “High temperature” is not enough to establish a material condition, wall thickness or inspection package. The supplier needs the purchase specification; the designer needs the service case that supports it.

[ASTM A312/A312M-25](https://store.astm.org/a0312_a0312m-25.html) identifies TP347H among grades intended for temperatures where creep and stress rupture properties matter. It does not publish a universal allowable operating temperature for every assembled 347H piping system in its public scope.

## Which temperatures should be recorded?

| Operating case       | Information to supply                                   | Review purpose                                                    |
| -------------------- | ------------------------------------------------------- | ----------------------------------------------------------------- |
| Normal operation     | Metal or fluid temperature basis, pressure and duration | Defines the expected duty                                         |
| Design case          | Design temperature, pressure and applicable code        | Connects the material order to the design calculation             |
| Startup and shutdown | Frequency and relevant temperature changes              | Identifies cyclic conditions for design review                    |
| Upset condition      | Maximum excursion, duration and frequency               | Prevents a normal-operation value from hiding an exceptional case |

These are project inputs, not temperature limits. Distinguish measured fluid temperature from the metal-temperature basis used in the design. If one is unknown, record it as unknown instead of substituting the other without review.

## Why does duration matter?

The standard’s reference to creep and stress rupture concerns time-dependent performance. A short excursion and continuous exposure are different design cases. Provide the intended operating profile and design life basis so the responsible engineer can apply the relevant code and material data.

Include the process atmosphere and cleaning environment. Elevated-temperature strength is one selection criterion; corrosion, fabrication and compatibility remain separate requirements. A grade chosen for one property does not settle the others.

## What belongs in the supplier’s technical response?

Ask for the exact grade, standard edition, manufacturing route, proposed condition, dimensions, examination scope and documentation. State any supplementary requirements in the order. [A312’s scope](https://store.astm.org/a0312_a0312m-25.html) expressly allows additional testing requirements to be specified when required.

If the item is actually an exchanger or superheater tube, confirm whether [ASTM A213/A213M-25](https://store.astm.org/a0213_a0213m-25.html) is the project requirement. Its public scope describes distinct requirements for H grades. Do not substitute a pipe product description for a tube specification without checking the full requirements.

## Who closes each question?

The designer approves service suitability, code basis and wall calculations. Procurement controls the ordered description and deviations. The supplier confirms the offered product and documents. Inspection checks the delivered evidence against the agreed requirements.

For an illustrative review, suppose the enquiry gives a normal operating temperature but no design temperature or excursion duration. The correct next step is to obtain those missing design inputs. A quotation can state its assumptions, but that does not close the engineering review.

Junda lists [347H seamless pipe](https://jundapipe.com/products/347h-seamless-stainless-steel-pipe). [Catalogue source](https://jundapipe.com/products) Submit the service sheet and purchase specification through the [contact page](https://jundapipe.com/contact). Keep unresolved items visible until the technical offer, design approval and order describe the same requirement.