* First combined union stoppage action in decades at Pilbara

* BHP's daily iron ore exports from Port Hedland at $80 mln

* Unions, BHP have a scheduled meet on July 14

(Adds details in paragraph 3,6,14-15, updates share price move

in paragraph 10)

By Melanie Burton

MELBOURNE, July 8 (Reuters) - Hundreds of workers at BHP's

Port Hedland iron ore operations in Western Australia could walk

off the job next week, in what would mark the biggest industrial

action there in decades, potentially disrupting $80 million of

daily revenue for BHP.

The unions have called for the action, an eight-hour work

stoppage set for July 16, after six months of negotiations that

have failed to reach an agreement on terms for a four-year

labour deal. The action is set to run from 2 p.m. to 10 p.m.

(0600 to 1400 GMT).

Some 160-200 employees of the 450 workers who cover BHP's

port and maintenance operations will walk off the job,

according to the Combined Ports Unions, which represents four

unions active at the site.

"This is nobody's preferred way forward, but when it is our

only way forward, we will take it," said Adam Woodage, the

secretary of the Electrical Trade Union Western Australia.

"I hope this sharpens the minds of BHP managers -- and

shareholders -- on the importance of negotiating for a fair,

safe and productive iron ore industry."

Union officials said a meeting with BHP was slated for

Tuesday that could avert the stoppage.

The action comes after workers at some of BHP's other

operations in the Pilbara region where Port Hedland is located

narrowly voted last week to approve a new labour agreement.

"We have delivered a new enterprise agreement at Mining Area

C and South Flank that rewards 1,800 workers -- without

industrial action," BHP said in a statement on Wednesday.

"Every Australian benefits from a strong iron ore sector. We

are eager to keep negotiating constructively for a fair deal,

while making sure we can keep operations running safely."

BHP shares fell 2.9% on the day to A$57.19 ($39.70),

slightly outpacing losses among other miners and compared to a

0.5% decline for Australia's benchmark stock index.

Unions are making the biggest push in 30 years to penetrate

Australia's mining heartland, emboldened by a Labor government

law in 2022 giving them the power to negotiate wage deals that

cover several employers, allow more scope to request flexible

arrangements and industry-wide strikes.

The South Flank agreement last week included a guaranteed

16% pay hike over its four-year term, increases to site-based

allowances and a new payment scheme for delayed flights.

"We think the South Flank deal is undercooked, for the work

that they do away from their family and for the conditions,"

Steve McCartney, state secretary of the Australian Manufacturing

Workers Union, told reporters. "Sixteen percent over four years

is not enough."

Mining workers are among Australia's best paid. Resources

workers living in the Pilbara earned A$191,000 on average in

2023-24, according to a survey by industry group the Chamber of

Minerals and Energy (CME).

Australia's median wage for registered nurses is A$85,000 to

A$100,000 according to industry bodies and the median wage is

A$75,000 a year, according to government figures.

Port Hedland, which is also used by miners Fortescue

and Hancock Prospecting, ships around $150 million of

iron ore a day.

($1 = 1.4407 Australian dollars)